target-i386: Change gen_op_add_reg_* size parameter to TCGMemOp

target-i386: Change gen_op_add_reg_* size parameter to TCGMemOp

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: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>