hwmon: qpnp-adc: Set correct adc_drv to NULL

Fix setting the correct adc_drv to NULL on error path during
probe.

Change-Id: I7923f79b65cc6303a1a31429287fcef356522d68
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
2 files changed