clk: clk-apple-nco: Add NULL check in applnco_probe

Add NULL check in applnco_probe, to handle kernel NULL pointer
dereference error.

Fixes: 6641057d ("clk: clk-apple-nco: Add driver for Apple NCO")
Signed-off-by: Charles Han <hanchunchao@inspur.com>
Link: https://lore.kernel.org/r/20241114072820.3071-1-hanchunchao@inspur.com


Reviewed-by: Martin Povišer <povik+lin@cutebit.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>