arm: support SDIV/UDIV in the disassembler

Currently UDIV and SDIV can not be correctly decoded. This patch
adds support for them and corresponding tests.

fixes #20096

Change-Id: I8818c29bc03aa9f0aaf157bfa03cd39114e0925e
Reviewed-on: https://go-review.googlesource.com/41891
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
3 files changed