Remove _S version of ARM MSR/MRS special registers

Remove _S version of ARM MSR/MRS special registers

2016-08-25  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* config/tc-arm.c (v7m_psrs): Remove msp_s, MSP_S, psp_s and PSP_S
	special registers.
	* testsuite/gas/arm/archv8m-cmse-msr.s: Remove test for above special
	registers.
	* testsuite/gas/arm/archv8m-cmse-msr-base.d: Likewise.
	* testsuite/gas/arm/archv8m-cmse-msr-main.d: Likewise.
	* testsuite/gas/arm/archv8m-main-dsp-4.d: Likewise.