drm/amd/display: shrink struct members

drm/amd/display: shrink struct members

On a 32-bit ARM system, the audio_decoder struct ends up being too large
for dp_retrain_link_dp_test.

link_dp_cts.c:157:1: error: the frame size of 1328 bytes is larger than
1280 bytes [-Werror=frame-larger-than=]

This is mitigated by shrinking the members of the struct and avoids
having to deal with dynamic allocation.

feed_back_divider is assigned but otherwise unused. Remove both.

pixel_repetition looks like it should be a bool since it's only ever
assigned to 1. But there are checks for 2 and 4. Reduce to uint8_t.

Remove ss_percentage_divider. Unused.

Shrink refresh_rate as it gets assigned to at most a 3 digit integer
value.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 3849efdc7888d537f09c3dcfaea4b3cd377a102e)