Add flash support for SiFive's Freedom E platforms

Valgrind and Clang Static Analyzer have no complaints about this change.

Change-Id: I7757615ec52448372bdc57729cdf97c7016d97e8
Signed-off-by: Tim Newsome <tim@sifive.com>
Reviewed-on: http://openocd.zylin.com/4656
Tested-by: jenkins
Reviewed-by: Philipp Guehring <pg@futureware.at>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

src/flash/nor/Makefile.am

@@ -27,6 +27,7 @@ NOR_DRIVERS = \
 	%D%/em357.c \
 	%D%/esirisc_flash.c \
 	%D%/faux.c \
+	%D%/fespi.c \
 	%D%/fm3.c \
 	%D%/fm4.c \
 	%D%/jtagspi.c \

src/flash/nor/drivers.c

@@ -42,6 +42,7 @@ extern struct flash_driver esirisc_flash;
 extern struct flash_driver faux_flash;
 extern struct flash_driver fm3_flash;
 extern struct flash_driver fm4_flash;
+extern struct flash_driver fespi_flash;
 extern struct flash_driver jtagspi_flash;
 extern struct flash_driver kinetis_flash;
 extern struct flash_driver kinetis_ke_flash;
@@ -109,6 +110,7 @@ static struct flash_driver *flash_drivers[] = {
 	&faux_flash,
 	&fm3_flash,
 	&fm4_flash,
+	&fespi_flash,
 	&jtagspi_flash,
 	&kinetis_flash,
 	&kinetis_ke_flash,