Added SPIFI flash driver, algorithms, and docs

Added a flash driver designed to allow program/erase of
memory-mapped SPI flash chips for LPC43xx/LPC18xx family
micros. This driver includes three algorithms - erase,
write, and SPIFI peripheral initialization (to allow
memory-mapped access after a reset). The driver has been
added to the flash driver table (drivers.c), and the
OpenOCD documentation has been updated to include the flash
driver configuration command.

Change-Id: I79f4ff8f1f07de4e5f2fe4f8c23aeb903f868514
Signed-off-by: George Harris <george@luminairecoffee.com>
Reviewed-on: http://openocd.zylin.com/783
Tested-by: jenkins
Reviewed-by: Aurelien Jacobs <aurel@gnuage.org>
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>

doc/openocd.texi

@@ -4652,6 +4652,30 @@ flash bank $_FLASHNAME cfi 0x00000000 0x02000000 2 4 $_TARGETNAME
 @c "cfi part_id" disabled
 @end deffn
 
+@deffn {Flash Driver} lpcspifi
+@cindex NXP SPI Flash Interface
+@cindex SPIFI
+@cindex lpcspifi
+NXP's LPC43xx and LPC18xx families include a proprietary SPI
+Flash Interface (SPIFI) peripheral that can drive and provide
+memory mapped access to external SPI flash devices.
+
+The lpcspifi driver initializes this interface and provides
+program and erase functionality for these serial flash devices.
+Use of this driver @b{requires} a working area of at least 1kB
+to be configured on the target device; more than this will
+significantly reduce flash programming times.
+
+The setup command only requires the @var{base} parameter. All
+other parameters are ignored, and the flash size and layout
+are configured by the driver.
+
+@example
+flash bank $_FLASHNAME lpcspifi 0x14000000 0 0 0 $_TARGETNAME
+@end example
+
+@end deffn
+
 @deffn {Flash Driver} stmsmi
 @cindex STMicroelectronics Serial Memory Interface
 @cindex SMI