video: adf: ensure consistent alignment on userspace facing structs

64-bit types in structs create alignment problems when a 32-bit x86
userspace talks to an x86_64 kernel.  In most cases the 64-bit types can
be replaced with 32-bit ones, since they're being used for fds and
should have been __s32 in the first place.  For adf_vsync_event,
alignment can be enforced by making the timestamp an __aligned_u64.

Change-Id: I87cf73d8f57730bd7bb43ffce6b7b411eb0ff198
Signed-off-by: Greg Hackmann <ghackmann@google.com>