uboot-imx

serial: sh: Enable clock if available

If the clock framework provides the driver with valid clock,
enable them, otherwise the SCIF might not work if the clock
are not enabled prior to the driver probe.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>