clk: clocking-wizard: check return value of devm_kasprintf()

devm_kasprintf() returns a pointer to dynamically allocated memory.
Pointer could be NULL in case allocation fails. Check pointer validity.
Identified with coccinelle (kmerr.cocci script).

Fixes: 2046338d ("ARM: mxs: Use soc bus infrastructure")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20230530093913.1656095-9-claudiu.beznea@microchip.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>