allow flash/nand banks commands to accept names

Add get_flash_bank_by_name (and get_nand_device_by_name) helpers
to retrieves struct flash_bank * (struct nand_device *) given a
driver name and an (optional) driver-specific bank index.

These are used to extend flash_command_get_bank_by_num (and
nand_command_get_device_by_num) to allow all flash (nand) commands to
reference defined banks by name, not just by number.

To avoid some code duplication, add the flash/common.[ch] files to hold
functionality common to both types driver.  The first two methods are
helpers for the above routines to find a bank specified by a "name" or
"name.index" string.  get_flash_name_index() finds the '.index' portion,
while flash_driver_name_matches() performs the string portion matching.

src/flash/common.h

@@ -0,0 +1,39 @@
+/***************************************************************************
+ *   Copyright (C) 2009 by Zachary T Welch <zw@superlucidity.net>          *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+#ifndef FLASH_COMMON_H
+#define FLASH_COMMON_H
+
+#include "types.h"
+
+/**
+ * Parses the optional '.index' portion of a flash bank identifier.
+ * @param name The desired driver name, passed by the user.
+ * @returns The parsed index request, or 0 if not present.  If the
+ * name provides a suffix but it does not parse as an unsigned integer, 
+ * the routine returns ~0U.  This will prevent further matching.
+ */ 
+unsigned get_flash_name_index(const char *name);
+/**
+ * Attempt to match the @c expected name with the @c name of a driver.
+ * @param name The name of the driver (from the bank's device structure).
+ * @param expected The expected driver name, passed by the user.
+ */
+bool flash_driver_name_matches(const char *name, const char *expected);
+
+#endif // FLASH_COMMON_H