In drmmode_output_init() check possible_crtcs for all encoders
In drmmode_output_init() check possible_crtcs for all encoders

drmmode_output_init() now determines the connector's possible_crtcs as
the set of crtcs which are possible for all encoders on that connector.
(Previously only encoder 0 was used)
Also calculates possible output clones using all encoders.
Includes some renaming for clarity.

Change-Id: I9cc1777d5160ce35bceaa7121bf9a70bb8d5a37c

singulared/xf86-video-armsoc,OtherCrashOverride/armsoc-hardkernel,freedesktop-unofficial-mirror/xorg__driver__xf86-video-armsoc,mmind/xf86-video-armsoc,commshare/xf86-video-armsoc,Popolon/xf86-video-armsoc,sbambrough/xf86-video-armsoc,mmind/xf86-video-armsoc,apxii/xf86-video-armsoc,freedesktop-unofficial-mirror/xorg__driver__xf86-video-armsoc,Popolon/xf86-video-armsoc,sbambrough/xf86-video-armsoc,singulared/xf86-video-armsoc,mdrjr/xf86-video-armsoc,commshare/xf86-video-armsoc,apxii/xf86-video-armsoc,mdrjr/xf86-video-armsoc,OtherCrashOverride/armsoc-hardkernel,xin3liang/xf86-video-armsoc,xin3liang/xf86-video-armsoc