[AArch64] Use aarch64_reg_or_imm instead of nonmemory_operand

[AArch64] Use aarch64_reg_or_imm instead of nonmemory_operand

Some of the shift expanders accepted nonmemory_operands but were only
able to handle register_operands or CONST_INTs.  This is probably
academic without SVE, since we're not likely to see shifts by other
types of constant (const_wide_ints, consts, etc).  But for SVE,
it's possible for a vectorised shift induction to have a CONST_POLY_INT
shift amount.

This patch makes the expanders use aarch64_reg_or_imm instead.

2017-11-07  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* config/aarch64/aarch64.md (ashl<mode>3, ashr<mode>3, lshr<mode>3)
	(rotr<mode>3, rotl<mode>3): Use aarch64_reg_or_imm instead of
	nonmmory_operand.

From-SVN: r254499