drm/amd/display: Create a file dedicated to planes

[Why]
The amdgpu_dm file contains most of the code that works as an interface
between DRM API and DC. As a result, this file becomes very large since
it comprises multiple abstractions such as plane manipulation.

[How]
This commit extracts the plane code to its specific file named
amdgpu_dm_plane. This change does not change anything inside the
functions; the only exception is converting some static functions to a
global function.

Tested-by: Daniel Wheeler <[email protected]>
Reviewed-by: Harry Wentland <[email protected]>
Acked-by: Alan Liu <[email protected]>
Signed-off-by: Rodrigo Siqueira <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Rodrigo Siqueira

drivers/gpu/drm/amd/display/amdgpu_dm/Makefile

@@ -25,7 +25,12 @@
 
 
 
-AMDGPUDM = amdgpu_dm.o amdgpu_dm_irq.o amdgpu_dm_mst_types.o amdgpu_dm_color.o
+AMDGPUDM = \
+	amdgpu_dm.o \
+	amdgpu_dm_plane.o \
+	amdgpu_dm_irq.o \
+	amdgpu_dm_mst_types.o \
+	amdgpu_dm_color.o
 
 ifdef CONFIG_DRM_AMD_DC_DCN
 AMDGPUDM += dc_fpu.o