drm_hwcomposer: Wrap libdrm drmMode*{Get|Free}* into RAII

This should elliminate chance of any leaks in the future.
Fix drmModePropertyBlobPtr leak in DrmHwcTwo.cpp.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
diff --git a/DrmHwcTwo.cpp b/DrmHwcTwo.cpp
index d9ba4f3..968d3ce 100644
--- a/DrmHwcTwo.cpp
+++ b/DrmHwcTwo.cpp
@@ -962,9 +962,9 @@
     uint8_t *outPort, uint32_t *outDataSize, uint8_t *outData) {
   supported(__func__);
 
-  drmModePropertyBlobPtr blob = nullptr;
+  auto blob = connector_->GetEdidBlob();
 
-  if (connector_->GetEdidBlob(blob)) {
+  if (!blob) {
     ALOGE("Failed to get edid property value.");
     return HWC2::Error::Unsupported;
   }