[AArch64] Reject invalid immediate operands to MSR UAO

[AArch64] Reject invalid immediate operands to MSR UAO

In the instruction to write to the ARMv8.2 PSTATE field UAO,
MSR UAO, #<imm>, the immediate should be either 0 or 1 but GAS accepts
any unsigned 4-bit integer.

This patch implements the constraint on the immediate, generating an
error if the immediate operand is invalid, and adds tests for the
illegal forms.

opcodes/
2016-01-20  Matthew Wahab  <matthew.wahab@arm.com>

	* aarch64-opc.c (operand_general_constraint_met_p): Check validity
	of MSR UAO immediate operand.

gas/
2016-01-20  Matthew Wahab  <matthew.wahab@arm.com>

	* testsuite/gas/aarch64/armv8_2-a-illegal.d: New.
	* testsuite/gas/aarch64/armv8_2-a-illegal.l: New.
	* testsuite/gas/aarch64/armv8_2-a-illegal.s: New.

Change-Id: Ibdec4967c00b1ef3be9dbc43d23b2c70d1a0b28c