drm/i915: Reinstate the mmap ioctl for some platforms

Reinstate the mmap ioctl for all current integrated platforms.
The intention was really to have it disabled for discrete graphics
where we enforce a single mmap mode.

This was reported to break ADL-P with the media stack, which was not the
intention. Although longer term we do still plan to sunset this ioctl
even for integrated, in favour of using mmap_offset instead.

Fixes: 35cbd91e

 ("drm/i915: Disable mmap ioctl for gen12+")
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210624112914.311984-1-thomas.hellstrom@linux.intel.com