flash/nor: Add support for TI CC3220SF internal flash

flash/nor: Add support for TI CC3220SF internal flash

Added cc3220sf flash driver to support the TI CC3220SF
microcontrollers. Implemented flash driver to support the
internal flash of the CC3220SF. The implementation does not
support the serial flash of the CC32xx family that requires
connection over UART, and not via JTAG/SWD debug. Added config
files for both CC32xx devices (no flash) and CC3220SF (with
flash).

Updated to implement comments from code review.
Additional updates to handle remaining comments from review.
Additional updates per review.

Added code to only request aligned writes and full 32-bit
words down to flash helper algorithm. Updated for recent
changes in OpenOCD flash code.

Removed cc32xx.cfg file made obsolete by this patch.
Change-Id: I58fc1478d07238d39c7ef02339f1097a91668c47
Signed-off-by: Edward Fewell <efewell@ti.com>
Reviewed-on: http://openocd.zylin.com/4319
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>