[media] exynos4-is: Fix driver name reported in vidioc_querycap

[media] exynos4-is: Fix driver name reported in vidioc_querycap

Originally struct v4l2_capability driver and card name was filled
with name of the platform device. After switching to the device tree
the device names have changed and now are 4 different driver names
reported, depending on the video device opened. So instead of e.g.
"exynos4-fimc" there is now one of: 11800000.fimc, 11810000.fimc,
11820000.fimc, 11830000.fimc.
Fix this by using dev->driver_name, rather than platform device name.
A common vidioc_querycap function is created for both M2M and capture
video node.
This fixes any breakage at user space should any application/library
rely on the driver's name.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>