spi: bcm-qspi: Fix missing clk_disable_unprepare() on error in bcm_qspi_probe()

Fix the missing clk_disable_unprepare() before return
from bcm_qspi_probe() in the error handling case.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20211018073413.2029081-1-yangyingliang@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>