devm_kzalloc will return NULL pointer if no memory was allocated.
This should be checked.  This problem also existed when the driver
was dell-wmi.c.
Signed-off-by: NMario Limonciello <mario.limonciello@dell.com>
Reviewed-by: NPali Rohár <pali.rohar@gmail.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>