[AArch64] Allow logical immediates to have all-1 in top bits

So that constant expressions like the following are permitted:

and w0, w0, #~(0xfe<<24)
and w1, w1, #~(0xff<<24)

The behavior matches GNU as (opcodes/aarch64-opc.c:aarch64_logical_immediate_p).

Reviewed By: sdesmalen

Differential Revision: https://reviews.llvm.org/D75885