accel/habanalabs: make gaudi2_is_device_idle() static

This function is only called inside gaudi2.c file.
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202303071320.X5ouBlNY-lkp@intel.com/Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
Reviewed-by: Ofir Bitton <obitton@habana.ai>

drivers/accel/habanalabs/gaudi2/gaudi2.c

@@ -7276,7 +7276,7 @@ static bool gaudi2_get_rotator_idle_status(struct hl_device *hdev, u64 *mask_arr
 	return is_idle;
 }
 
-bool gaudi2_is_device_idle(struct hl_device *hdev, u64 *mask_arr, u8 mask_len,
+static bool gaudi2_is_device_idle(struct hl_device *hdev, u64 *mask_arr, u8 mask_len,
 					struct engines_data *e)
 {
 	bool is_idle = true;