clk: exynos: add function for Samsung CMU ops->request

clk: exynos: add function for Samsung CMU ops->request

The request function performs a simple check if the clock with the
provided ID is present or not. This is done with a simple call to
clk_get_by_id(). A non-zero return value indicates that the requested
clock is not available.

In some cases, clk->dev points to the clock bank device instead of
the clock device. This pointer is therefore overwritten in order to
reference to the correct device instance.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>