drm/amd/display: Fix naming of DSC Debugfs entry

[why]
Fix naming and return bits rather than bytes per pixel for
naming consistency. Because registers return Bytes per pixel,
but DSC Config structure is expecting bits per pixel as input.
So when returning the value convert from bytes into bits.

Signed-off-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Reviewed-by: Mikita Lipski <Mikita.Lipski@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>