cmd/asm: fix encoding errors for FMOVD and FMOVS instructions on arm64
The encoding of instructions "FMOVD F1, ZR" and "FMOVS F1, ZR" is wrong,
the assembler encodes them as "FMOVD F1, F31" and "FMOVS F1, F31". This
CL fixes the bug.
Change-Id: I2d31520b58f9950ce2534a04f4a3275bf103a673
Reviewed-on: https://go-review.googlesource.com/c/go/+/503135
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Eric Fang <eric.fang@arm.com> Reviewed-by: Cherry Mui <cherryyz@google.com>