radeon/uvd: don't expose HEVC on old UVD hw (v3)

radeon/uvd: don't expose HEVC on old UVD hw (v3)

The section for UVD 2 and older was not updated
when HEVC support was added. Reported by Kano
on irc.

v2: integrate the UVD2 and older checks into the
main switch statement.
v3: handle encode checking as well.  Encode is
already checked in the top case statement, so
drop encode checks in the lower case statement.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: mesa-stable@lists.freedesktop.org