spi: pxa2xx: Remove the unneeded result variable

Return the value clk_prepare_enable() directly instead of storing it in
another redundant variable.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Link: https://lore.kernel.org/r/20220825072828.229294-1-ye.xingchen@zte.com.cn


Signed-off-by: Mark Brown <broonie@kernel.org>