Fix spelling of ARM Cortex

It's Cortex-Xn, not Cortex Xn or cortex xn or cortex-xn or CORTEX-Xn
or CortexXn. Further it's Cortex-M0+, not M0plus.

Cf. http://www.arm.com/products/processors/index.php

Consistently write it the official way, so that it stops propagating.
Originally spotted in the documentation, it mainly affects code comments
but also Atmel SAM3/SAM4/SAMV, NiietCM4 and SiM3x flash driver output.

Found via:

  git grep -i "Cortex "
  git grep -i "Cortex-" | grep -v "Cortex-" | grep -v ".cpu"
  git grep -i "CortexM"

Change-Id: Ic7b6ca85253e027f6f0f751c628d1a2a391fe914
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-on: http://openocd.zylin.com/3483
Tested-by: jenkins
Reviewed-by: Marc Schink <openocd-dev@marcschink.de>
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>

contrib/loaders/flash/cortex-m0.S

@@ -27,8 +27,8 @@
 
 /* Written for NRF51822 (src/flash/nor/nrf51.c) however the NRF NVMC is
  * very generic (CPU blocks during flash writes), so this is actually
- * just a generic word-oriented copy routine for cortex-m0 (also
- * suitable for cortex m0plus/m3/m4.)
+ * just a generic word-oriented copy routine for Cortex-M0 (also
+ * suitable for Cortex-M0+/M3/M4.)
  *
  * To assemble:
  * arm-none-eabi-gcc -c cortex-m0.S