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>

src/rtos/rtos_standard_stackings.c

@@ -182,7 +182,7 @@ int64_t rtos_generic_stack_align8(struct target *target,
 			stacking, stack_ptr, 8);
 }
 
-/* The Cortex M3 will indicate that an alignment adjustment
+/* The Cortex-M3 will indicate that an alignment adjustment
  * has been done on the stack by setting bit 9 of the stacked xPSR
  * register.  In this case, we can just add an extra 4 bytes to get
  * to the program stack.  Note that some places in the ARM documentation