mfd: qcom_rpm: Fix an error handling path in qcom_rpm_probe()

[ Upstream commit 36579aca ]

If an error occurs after the clk_prepare_enable() call, a corresponding
clk_disable_unprepare() should be called.

Simplify code and switch to devm_clk_get_enabled() to fix it.

Fixes: 35264033

 ("mfd: qcom_rpm: Handle message RAM clock")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/e39752476d02605b2be46cab7115f71255ce13a8.1668949256.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Sasha Levin <sashal@kernel.org>