spi: sp7201: Fix compiler warnings

Fix compiler warming for kernel test

Fixes: f62ca4e2 ("spi: Add spi driver for Sunplus SP7021")
Signed-off-by: Li-hao Kuo <lhjeff911@gmail.com>
Link: https://lore.kernel.org/r/CAGcXWkzM6wbhNFLbYoijq7iS_76nYVod1ySFEDu-BRgnBokEQA@mail.gmail.com


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