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>

tcl/target/amdm37x.cfg

@@ -199,7 +199,7 @@ $_TARGETNAME configure -event gdb-attach {
 # Run this to enable invasive debugging.  This is run automatically in the
 # reset sequence.
 proc amdm37x_dbginit {target} {
-   # General Cortex A8 debug initialisation
+   # General Cortex-A8 debug initialisation
    cortex_a dbginit
 
    # Enable DBGEN signal.  This signal is described in the ARM v7 TRM, but