drm/radeon/atom: workaround vbios bug in transmitter table on rs880 (v2)

drm/radeon/atom: workaround vbios bug in transmitter table on rs880 (v2)

The OUTPUT_ENABLE action jumps past the point in the coder where
the data_offset is set on certain rs780 cards.  This worked
previously because the OUTPUT_ENABLE action is always called
immediately after the ENABLE action so the data_offset remained
set.  In 6f8bbaf568c7f2c497558bfd04654c0b9841ad57
(drm/radeon/atom: initialize more atom interpretor elements to 0),
we explictly reset data_offset to 0 between atom calls which then
caused this to fail.  The fix is to just skip calling the
OUTPUT_ENABLE action on the problematic chipsets.  The ENABLE
action does the same thing and more.  Ultimately, we could
probably drop the OUTPUT_ENABLE action all together on DCE3
asics.

fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=60791

v2: only rs880 seems to be affected

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org