clk: samsung: fixed compiler warning [-Wpointer-to-int-cast]

When compiled using ARM64 cross compiler, gcc complains as

drivers/clk/samsung/clk.c:293:18:
warning: cast from pointer to integer of different size
[-Wpointer-to-int-cast]

Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Signed-off-by: Tomasz Figa <t.figa@samsung.com>