Documentation/gpu: remove duplicate entries in different glossaries

Some items were defined in both the general and DC glossaries.
Remove the duplicate entries.

Fixes: 2df30ae0ba0b ("Documentation/gpu: Add acronyms for some firmware components")
Reported-by: Stephen Rothwell <[e-mail]>
Cc: Rodrigo Siqueira <[e-mail]>
Reviewed-by: Rodrigo Siqueira <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

Documentation/gpu/amdgpu/display/dc-glossary.rst

···
     MALL
       Memory Access at Last Level
 
-    MC
-      Memory Controller
-
     MPC/MPCC
       Multiple pipes and plane combine
 
···
 
     VRR
       Variable Refresh Rate
-
-    UVD
-      Unified Video Decoder