Code for creating single byte llis is present at several places. Create a
routine to avoid code redundancy.

Also, we don't need one lli per single byte transfer, we can have single lli to
do all single byte transfer.
Signed-off-by: NViresh Kumar <viresh.kumar@st.com>
Acked-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>