These functions used the aflags/dflags domain, which is log2-1
of the byte size.  Confusingly, they used enumeration values
from the log2 domain.

Change the domain of the parameter and update all callers.

Since we're now in a common domain, defer the deposit/extend/mov
decision to gen_op_mov_reg_v.
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRichard Henderson <rth@twiddle.net>