usb: ehci-exynos: Use devm_clk_get_enabled() helpers

usb: ehci-exynos: Use devm_clk_get_enabled() helpers

The devm_clk_get_enabled() helpers:
    - call devm_clk_get()
    - call clk_prepare_enable() and register what is needed in order to
     call clk_disable_unprepare() when needed, as a managed resource.

This simplifies the code and avoids the calls to clk_disable_unprepare().

Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20240412142317.5191-2-linux.amoon@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>