phy: move clk enable/disable in init/exit

phy: move clk enable/disable in init/exit

It is better to place clk_enable() in phy_meson_g12a_usb2_init()
and clk_disable() in phy_meson_g12a_usb2_exit().

For more detailed information, please see comments in the review of
a similar driver in the Linux Kernel:

https://lore.kernel.org/all/CAFBinCCEhobbyKHuKDWzTYCQWgNT1-e8=7hMhq1mvT6CuEOjGw@mail.gmail.com/

Signed-off-by: Alexey Romanov <avromanov@salutedevices.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20231005085434.74755-5-avromanov@salutedevices.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>