[PATCH] staging: atomisp: move null check to earlier point

[Cengiz Can]

`find_gmin_subdev` function that returns a pointer to `struct
gmin_subdev` can return NULL.

In `gmin_v2p8_ctrl` there's a call to this function but the possibility
of a NULL was not checked before its being dereferenced. ie:

```
/* Acquired here --------v */
struct gmin_subdev *gs = find_gmin_subdev(subdev);
int ret;
int value;

/*  v------Dereferenced here */
if (gs->v2p8_gpio >= 0) {
        pr_info("atomisp_gmin_platform: 2.8v power on GPIO %d\n",
                gs->v2p8_gpio);
        ret = gpio_request(gs->v2p8_gpio, "camera_v2p8");
        if (!ret)
                ret = gpio_direction_output(gs->v2p8_gpio, 0);
        if (ret)
                pr_err("V2P8 GPIO initialization failed\n");
}
```

I have moved the NULL check before deref point.

Caught-by: Coverity Static Analyzer CID 1465536
Signed-off-by: Cengiz Can <cen...@kernel.wtf>
---
 drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c 
b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
index 0df46a1af5f0..8e9c5016f299 100644
--- a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
+++ b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
@@ -871,6 +871,11 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev, int 
on)
        int ret;
        int value;
 
+       if (!gs) {
+               pr_err("Unable to find gmin subdevice\n");
+               return -EINVAL;
+       }
+
        if (gs->v2p8_gpio >= 0) {
                pr_info("atomisp_gmin_platform: 2.8v power on GPIO %d\n",
                        gs->v2p8_gpio);
@@ -881,7 +886,7 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev, int 
on)
                        pr_err("V2P8 GPIO initialization failed\n");
        }
 
-       if (!gs || gs->v2p8_on == on)
+       if (gs->v2p8_on == on)
                return 0;
        gs->v2p8_on = on;
 
-- 
2.27.0

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