[AArch64][SVE 19/32] Refactor address-printing code

[AArch64][SVE 19/32] Refactor address-printing code

SVE adds addresses in which the base or offset are vector registers.
The addresses otherwise have the same kind of form as normal AArch64
addresses, including things like SXTW with or without a shift, UXTW
with or without a shift, and LSL.

This patch therefore refactors the address-printing code so that it
can cope with both scalar and vector registers.

opcodes/
	* aarch64-opc.c (get_offset_int_reg_name): New function.
	(print_immediate_offset_address): Likewise.
	(print_register_offset_address): Take the base and offset
	registers as parameters.
	(aarch64_print_operand): Update caller accordingly.  Use
	print_immediate_offset_address.