flash/nor: Add support for Artery devices

Initial driver for Artery devices without flash loader and dual-bank
support. Tested with AT32F415CBT7 and AT32F421C8T7.

Change-Id: I3213f8403d0f3db5d205e200f626e73043f55834
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/8667
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

src/flash/nor/Makefile.am

@@ -12,6 +12,7 @@ NOR_DRIVERS = \
 	%D%/aduc702x.c \
 	%D%/aducm360.c \
 	%D%/ambiqmicro.c \
+	%D%/artery.c \
 	%D%/at91sam4.c \
 	%D%/at91sam4l.c \
 	%D%/at91samd.c \
@@ -85,6 +86,7 @@ NOR_DRIVERS = \
 	%D%/xmc4xxx.c
 
 NORHEADERS = \
+	%D%/artery.h \
 	%D%/core.h \
 	%D%/cc3220sf.h \
 	%D%/bluenrg-x.h \