media: dvb-frontends: mn88443x: Handle errors of clk_prepare_enable()

mn88443x_cmn_power_on() did not handle possible errors of
clk_prepare_enable() and always finished successfully so that its caller
mn88443x_probe() did not care about failed preparing/enabling of clocks
as well.

Add missed error handling in both mn88443x_cmn_power_on() and
mn88443x_probe(). This required to change the return value of the former
from "void" to "int".

Found by Linux Driver Verification project (linuxtesting.org).

Fixes: 0f408ce8 ("media: dvb-frontends: add Socionext MN88443x ISDB-S/T demodulator driver")
Signed-off-by: Evgeny Novikov <novikov@ispras.ru>
Co-developed-by: Kirill Shilimanov <kirill.shilimanov@huawei.com>
Signed-off-by: Kirill Shilimanov <kirill.shilimanov@huawei.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>