drm/amd/display: Drop CONFIG_DRM_AMD_DC_DMUB guards

[Why]
Support for DMUB only depends on support for DC. It doesn't use floating
point so we don't need to guard it by any specific DCN revision.

[How]
Drop the guards and cleanup the newlines around each one.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>