hwc/overlay/hdmi: Fix / enable some error messages.

Fix cases where some errors are really warnings/info.
Print one-time events like HDMI connect disconnect as info logs.
Print the error string and type on MSMFB_OVERLAY_PREPARE failure.

An ENODEV from driver corresponds to a pipe not available and should
be treated as a warning. This could happen if a previous UNSET is
pending due to a missed vsync. ENODEV should be treated as fatal
only if it is seen continuously representing a book-keeping
blunder.

Change-Id: I730d4ac7db84c287f47805b9c74792c90cfadc6c
diff --git a/libhwcomposer/hwc.cpp b/libhwcomposer/hwc.cpp
index fd3bb69..54e7c25 100644
--- a/libhwcomposer/hwc.cpp
+++ b/libhwcomposer/hwc.cpp
@@ -752,7 +752,7 @@
     bool isVirtualDisplay = (disp == HWC_DISPLAY_VIRTUAL);
     // If hotpluggable or virtual displays are inactive return error
     if ((hotPluggable || isVirtualDisplay) && !ctx->dpyAttr[disp].connected) {
-        ALOGE("%s display (%d) is inactive", __FUNCTION__, disp);
+        ALOGW("%s display (%d) is not connected anymore", __FUNCTION__, disp);
         return -EINVAL;
     }