drm: amd: Fix line continuation formats

Line continuations with excess spacing causes unexpected output.

Miscellanea:

o Added missing '\n' to a few of the coalesced pr_<level> formats

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>