spi: stm32-qspi: Always wait BUSY bit to be cleared in stm32_qspi_wait_cmd()

stable inclusion
from stable-5.10.46
commit 2f8f0e97cebb6c2b7cffd5b7c08331535680ae40
bugzilla: 168323
CVE: NA

--------------------------------

[ Upstream commit d38fa9a1 ]

In U-boot side, an issue has been encountered when QSPI source clock is
running at low frequency (24 MHz for example), waiting for TCF bit to be
set didn't ensure that all data has been send out the FIFO, we should also
wait that BUSY bit is cleared.

To prevent similar issue in kernel driver, we implement similar behavior
by always waiting BUSY bit to be cleared.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Link: https://lore.kernel.org/r/20210603073421.8441-1-patrice.chotard@foss.st.com


Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>