cmd/compile: enforce strongly typed rules for ARM (6)

End of "constant folding in *shift ops" until EOF
(L1070-)
Toolstash-check is successful.

Change-Id: I55846a459aca5238f831750f04132e13a0baeed7
Reviewed-on: https://go-review.googlesource.com/c/go/+/234198
Reviewed-by: Giovanni Bajo <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Trust: Giovanni Bajo <[email protected]>
Run-TryBot: Giovanni Bajo <[email protected]>
TryBot-Result: Go Bot <[email protected]>

Author: iwdgo