clk: versal: Mark versal_clock_setup() as static

Fix the following sparse and compile time warning
triggered with W=1:

drivers/clk/clk_versal.c:605:5:
warning: no previous prototype for 'versal_clock_setup'
[-Wmissing-prototypes]
605 | int versal_clock_setup(void)

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
Link: https://lore.kernel.org/r/20221007105535.31902-1-venkatesh.abbarapu@amd.com


Signed-off-by: Michal Simek <michal.simek@amd.com>