It is possible that on one of the error paths we are going to try to free
'rxbuf', even though it has not been allocated yet, which cause the following
warning:
	drivers/staging/iio/adc/max1363_ring.c: In function 'max1363_trigger_handler':
		drivers/staging/iio/adc/max1363_ring.c:87:7: warning: 'rxbuf' may be used
		uninitialized in this function
Reported-by: Fengguang Wu <wfg@linux.intel.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>