media: dm365_ipipe: remove an unused var

drivers/staging/media/davinci_vpfe/dm365_ipipe.c:74:17: warning: variable 'dev' set but not used [-Wunused-but-set-variable]
  struct device *dev;
                 ^~~

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>