media: staging: media: Make use of devm_platform_ioremap_resource

Fix below issue reported by coccicheck
drivers/staging//media/omap4iss/iss.c:915:1-15: WARNING: Use
devm_platform_ioremap_resource for iss -> regs [ res ]

Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>