Please silence fron camera driver warnings

I thought i broke something when building imx8-current-librem5 but then it was the camera:

drivers/media/i2c/hi846.c: In function ‘hi846_set_format’:
drivers/media/i2c/hi846.c:1038:18: warning: unused variable ‘h_blank’ [-Wunused-variable]
 1038 |  s32 vblank_def, h_blank;
      |                  ^~~~~~~
drivers/media/i2c/hi846.c:1038:6: warning: unused variable ‘vblank_def’ [-Wunused-variable]
 1038 |  s32 vblank_def, h_blank;
      |      ^~~~~~~~~~
drivers/media/i2c/hi846.c:1035:27: warning: unused variable ‘mode’ [-Wunused-variable]
 1035 |  const struct hi846_mode *mode;
      |                           ^~~~
At top level:
drivers/media/i2c/hi846.c:1241:13: warning: ‘hi846_gpio_deassert’ defined but not used [-Wunused-function]
 1241 | static void hi846_gpio_deassert(struct hi846 *hi846, int id)
      |             ^~~~~~~~~~~~~~~~~~~
drivers/media/i2c/hi846.c:530:12: warning: ‘hi846_capture_setting_normal_video_2’ defined but not used [-Wunused-function]
  530 | static int hi846_capture_setting_normal_video_2(struct hi846 *hi846)
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/media/i2c/hi846.c:472:12: warning: ‘hi846_capture_setting_normal_video’ defined but not used [-Wunused-function]
  472 | static int hi846_capture_setting_normal_video(struct hi846 *hi846)
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Would be coo to have fixed since this makes one miss errors in local builds. @martin.kepplinger since you're on that driver, could you fix that please?