overlay: Change max rotator sessions to 4 and log level

Change max rotator sessions to 4, since we could support upto
those many.

Change error log to warning log on reaching beyond max rotator
sessions, since its not really an error, but flagging it as one
raises false positives in testing filters.

Change-Id: Ib06a00bce57dfa9dbda3f2e6874a31ce1a155463
diff --git a/liboverlay/overlayRotator.cpp b/liboverlay/overlayRotator.cpp
index 0e5b0ec..0671b62 100644
--- a/liboverlay/overlayRotator.cpp
+++ b/liboverlay/overlayRotator.cpp
@@ -145,7 +145,7 @@
     //Return a rot object, creating one if necessary
     overlay::Rotator *rot = NULL;
     if(mUseCount >= MAX_ROT_SESS) {
-        ALOGE("%s, MAX rotator sessions reached", __func__);
+        ALOGW("%s, MAX rotator sessions reached, request rejected", __func__);
     } else {
         if(mRot[mUseCount] == NULL)
             mRot[mUseCount] = overlay::Rotator::getRotator();