clk: si5341: check return value of {devm_}kasprintf()

clk: si5341: check return value of {devm_}kasprintf()

[ Upstream commit 36e4ef82016a2b785cf2317eade77e76699b7bff ]

{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: 3044a860fd09 ("clk: Add Si5341/Si5340 driver")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20230530093913.1656095-5-claudiu.beznea@microchip.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>