phy: rockchip-pcie: Refactor mutex handling in rockchip_pcie_phy_power_off()

Refactor the mutex handling in the rockchip_pcie_phy_power_off() function
to improve code readability and maintainability. The goto statement has
been removed, and the mutex_unlock call is now directly within the
conditional block.

Return the result of reset_control_assert() function, with 0 indicating
success and an error code indicating failure

Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Link: https://lore.kernel.org/r/20241012071919.3726-5-linux.amoon@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>