media: v4l2-core: Remove BUG() from i2c and spi helpers

Currently, the i2c and spi subdev creation helpers
are calling BUG() when passed a NULL v4l2_device parameter.

This makes little sense; simply returning NULL seems more
sensible.

These two helpers may already return NULL on error, so callers
should already be checking for this, or at least be prepared
for a NULL result.

Signed-off-by: Ezequiel Garcia <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/v4l2-core/v4l2-i2c.c

···
 	struct v4l2_subdev *sd = NULL;
 	struct i2c_client *client;
 
-	BUG_ON(!v4l2_dev);
+	if (!v4l2_dev)
+		return NULL;
 
 	request_module(I2C_MODULE_PREFIX "%s", info->type);
 

drivers/media/v4l2-core/v4l2-spi.c

···
 	struct v4l2_subdev *sd = NULL;
 	struct spi_device *spi = NULL;
 
-	BUG_ON(!v4l2_dev);
-
+	if (!v4l2_dev)
+		return NULL;
 	if (info->modalias[0])
 		request_module(info->modalias);