[ARC] Update handling AUX-registers.

Update aux-registers data-base, and accept aux-registers names with
upper/lowercase names.

opcode/
2017-07-18  Claudiu Zissulescu  <claziss@synopsys.com>

	* arc-regs.h: Update aux-registers.

gas/
2017-07-18  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/tc-arc.c (find_opcode_match): Accept uppercase aux-regs
	names.
	* testsuite/gas/arc/ld2.d: Update test.
	* testsuite/gas/arc/taux.d: Likewise.
	* testsuite/gas/arc/taux.s: Likewise.

include/
2017-07-18  Claudiu Zissulescu  <claziss@synopsys.com>

	* opcode/arc.h (ARC_OPCODE_ARCV1): Define.