spi: Fix missing unlock on error in sp7021_spi_master_transfer_one()

Add the missing unlock before return from sp7021_spi_master_transfer_one()
in the error handling case.

Fixes: f62ca4e2 ("spi: Add spi driver for Sunplus SP7021")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20220127115815.3148950-1-yangyingliang@huawei.com


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