hwc: Don't permit rotator use under certain conditions

These include constrained targets, with external connected which could
lead to a scarcity of pipes. Furthermore owing to a scarcity of writeback
interfaces, even if pipes are available, we may not be able to still
use rotator.

Change-Id: Ie2fb4c1726f32addcace89c268a126abe0cddbe0
diff --git a/libqdutils/mdp_version.cpp b/libqdutils/mdp_version.cpp
index e328d23..cac6b1d 100644
--- a/libqdutils/mdp_version.cpp
+++ b/libqdutils/mdp_version.cpp
@@ -130,5 +130,10 @@
     // BWC - Bandwidth Compression
     return (mFeatures & MDP_BWC_EN);
 }
+
+bool MDPVersion::is8x26() {
+    return mMdpRev == MDSS_MDP_HW_REV_101;
+}
+
 }; //namespace qdutils