soc: aspeed: Add NULL check in aspeed_lpc_enable_snoop()

soc: aspeed: Add NULL check in aspeed_lpc_enable_snoop()

devm_kasprintf() returns NULL when memory allocation fails. Currently,
aspeed_lpc_enable_snoop() does not check for this case, which results in a
NULL pointer dereference.

Add NULL check after devm_kasprintf() to prevent this issue.

Fixes: 3772e5da4454 ("drivers/misc: Aspeed LPC snoop output using misc chardev")
Signed-off-by: Henry Martin <bsdhenrymartin@gmail.com>
Link: https://patch.msgid.link/20250401074647.21300-1-bsdhenrymartin@gmail.com
[arj: Fix Fixes: tag to use subject from 3772e5da4454]
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>