PM / devfreq: governor: Replace sscanf() with kstrtoul() in set_freq_store()

[ Upstream commit 914cc799 ]

Replace sscanf() with kstrtoul() in set_freq_store() and check the result
to avoid invalid input.

Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Link: https://lore.kernel.org/lkml/20250421030020.3108405-2-zhenglifeng1@huawei.com/


Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>