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/target/cortex_a.c

@@ -18,7 +18,7 @@
  *   michel.jaouen@stericsson.com : smp minimum support                    *
  *                                                                         *
  *   Copyright (C) Broadcom 2012                                           *
- *   ehunter@broadcom.com : Cortex R4 support                              *
+ *   ehunter@broadcom.com : Cortex-R4 support                              *
  *                                                                         *
  *   Copyright (C) 2013 Kamal Dasu                                         *
  *   kdasu.kdev@gmail.com                                                  *
@@ -2664,7 +2664,7 @@ out:
 /*
  * Cortex-A Memory access
  *
- * This is same Cortex M3 but we must also use the correct
+ * This is same Cortex-M3 but we must also use the correct
  * ap number for every access.
  */