cmd/compile: remove 4-byte alignment requirement of stack slot on arm

This CL applies CL 267999 to arm.

Updates #42385

Change-Id: Iad82aafcb7b0a5a77a4bea32f648320f57a17cdd
Reviewed-on: https://go-review.googlesource.com/c/go/+/297773
Reviewed-by: eric fang <eric.fang@arm.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Trust: eric fang <eric.fang@arm.com>
Run-TryBot: eric fang <eric.fang@arm.com>

src/cmd/compile/internal/ssagen/pgen.go

@@ -133,7 +133,7 @@ func (s *ssafn) AllocFrame(f *ssa.Func) {
 		} else {
 			lastHasPtr = false
 		}
-		if Arch.LinkArch.InFamily(sys.ARM, sys.PPC64) {
+		if Arch.LinkArch.InFamily(sys.PPC64) {
 			s.stksize = types.Rnd(s.stksize, int64(types.PtrSize))
 		}
 		n.SetFrameOffset(-s.stksize)