Revert "cherry-ignore: add the Flush after unmap in gbm/dri fix"

This reverts commit 3a84f6fd4330a00a8d89c24d569dbb450832602d.

The fix in question has been properly addressed and does not cause
regressions.
diff --git a/bin/.cherry-ignore b/bin/.cherry-ignore
index d97ff39..0bb90e2 100644
--- a/bin/.cherry-ignore
+++ b/bin/.cherry-ignore
@@ -3,6 +3,3 @@
 # The commit addressed an earlier commit 0567ab0407e which did not land in branch.
 # A stable specific backported patch will follow later ...
 bc5d587a80b64fb3e0a5ea8067e6317fbca2bbc5 radv: Invalidate L2 for TRANSFER_WRITE barriers
-# The commit caused a regression in i915 (and possibly others) since
-# it didn't implement v4 of DRI2's flush extension.
-ba8df2286a50117011925e915cd832b4a79f126e gbm/dri: Flush after unmap