pwm: Fix double shift bug

stable inclusion
from stable-v4.19.315
commit a98ff250b5af87f92f17bb9725cb21de1931ee57
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9R4KN
CVE: CVE-2023-52756

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v4.19.315&id=a98ff250b5af87f92f17bb9725cb21de1931ee57



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[ Upstream commit d27abbfd4888d79dd24baf50e774631046ac4732 ]

These enums are passed to set/test_bit().  The set/test_bit() functions
take a bit number instead of a shifted value.  Passing a shifted value
is a double shift bug like doing BIT(BIT(1)).  The double shift bug
doesn't cause a problem here because we are only checking 0 and 1 but
if the value was 5 or above then it can lead to a buffer overflow.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Wenyu Huang <huangwenyu5@huawei.com>