sh: generic_in/outs{bwl} optimizations.

After performing the port2addr conversion, and checking that the data is
correctly aligned, simply call __raw_readsX/writesX. These have already been
optimised.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>