rtc: mxc_v2: Add missing clk_disable_unprepare()

rtc: mxc_v2: Add missing clk_disable_unprepare()

[ Upstream commit 55d5a86618d3b1a768bce01882b74cbbd2651975 ]

The call to clk_disable_unprepare() is left out in the error handling of
devm_rtc_allocate_device. Add it back.

Fixes: 5490a1e018a4 ("rtc: mxc_v2: fix possible race condition")
Signed-off-by: GUO Zihua <guozihua@huawei.com>
Link: https://lore.kernel.org/r/20221122085046.21689-1-guozihua@huawei.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>