media: dm365_ipipeif: better annotate a fall though

Shut up this warning:

	drivers/staging/media/davinci_vpfe/dm365_ipipeif.c: In function 'ipipeif_hw_setup':
	drivers/staging/media/davinci_vpfe/dm365_ipipeif.c:298:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
	   switch (isif_port_if) {
	   ^~~~~~
	drivers/staging/media/davinci_vpfe/dm365_ipipeif.c:314:2: note: here
	  case IPIPEIF_SDRAM_YUV:
	  ^~~~

By annotating a fall though case at the right place.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>