serial: of_serial: check the return value of clk_prepare_enable()
serial: of_serial: check the return value of clk_prepare_enable()

The function clk_prepare_enable() may fail, and in that case it
does not make sense to proceed.  Let's check its return code and
error out if it is a negative value.

Signed-off-by: Masahiro Yamada <378b411a8a63ecc7605ec4272234862d7781c6ae@socionext.com>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs