Revert "hwc: Add support to query max. supported WriteBack width"

This reverts commit 744cc693f9bfd28b9313fa5261cf24c1df0d75b9.

Change-Id: I7a37059323d0a071765dce8d865cdfa0198a64de
diff --git a/libhwcomposer/hwc.cpp b/libhwcomposer/hwc.cpp
index db456bc..80e7803 100644
--- a/libhwcomposer/hwc.cpp
+++ b/libhwcomposer/hwc.cpp
@@ -484,9 +484,6 @@
     case HWC_COLOR_FILL:
         value[0] = 1;
         break;
-    case HWC_MAX_WRITEBACK_WIDTH:
-        value[0] = qdutils::MAX_DISPLAY_DIM;
-        break;
     default:
         return -EINVAL;
     }