media: atomisp: fix uninitialized bug in gmin_get_pmic_id_and_addr()

The "power" pointer is not initialized on the else path and that would
lead to an Oops.

Link: https://lore.kernel.org/linux-media/20211012082150.GA31086@kili
Fixes: c30f4cb2d4 ("media: atomisp: Refactor PMIC detection to a separate function")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c

@@ -500,7 +500,7 @@ fail:
 
 static u8 gmin_get_pmic_id_and_addr(struct device *dev)
 {
-	struct i2c_client *power;
+	struct i2c_client *power = NULL;
 	static u8 pmic_i2c_addr;
 
 	if (pmic_id)