[ Upstream commit c1a3acaa ]

There's no need to keep one local variable for clock, and
then assign the same to 'clk' member of dwc3_exynos.
Just cleaning it up.
Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>