surfaceflinger: fix -Wmismatched-tags warnings

warning: struct 'HWComposer' was previously declared as a class
[-Wmismatched-tags]

warning: class 'DisplayInfo' was previously declared as a struct
[-Wmismatched-tags]

Change-Id: I13db9f8aab3a957ce8ff8d64598dae1807d6fe7e
(cherry picked from commit 646f54105018e99ef4a30ee41f01f7d1ab66c38e)
3 files changed