serial: ucc_uart: replace ppc-specific IO accessors

Some ARM-based SOCs (e.g. LS1021A) also have a QUICC engine. As
preparation for allowing this driver to build on ARM, replace the
ppc-specific in_be16() etc. by the qe_io* helpers. Done via
coccinelle.
Reviewed-by: Timur Tabi <timur@kernel.org>
Acked-by: Timur Tabi <timur@kernel.org>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Li Yang <leoyang.li@nxp.com>