cmd/internal/obj/arm64: fix assemble VLD1/VST1 bug

The current code misassembles VLD1/VST1 instruction with non-zero
offset. The offset is dropped silently without any error message.
The cause of the misassembling is the current code treats argument
(Rn)(Rm) as ZOREG type.

The fix changes the matching rules and considers (Rn)(Rm) as ROFF
type. The fix will report error information when assembles VLD1/VST1
(R8)(R13), [V1.16B].
The fix enables the ARM64Errors test.

Fixes #23448

Change-Id: I3dd518b91e9960131ffb8efcb685cb8df84b70eb
Reviewed-on: https://go-review.googlesource.com/87956


Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>