qdMetadata: Use uint32_t instead of bool

Some graphics drivers don't recognize bool (^^) so use uint32_t
instead to fix compilation issues.

Change-Id: I12e13ed4d13ec241467a4c5a2b9cf2e409ee5505
diff --git a/libgralloc/mapper.cpp b/libgralloc/mapper.cpp
index 37e83bc..dcf2ee8 100644
--- a/libgralloc/mapper.cpp
+++ b/libgralloc/mapper.cpp
@@ -483,7 +483,7 @@
         case GRALLOC_MODULE_PERFORM_SET_SINGLE_BUFFER_MODE:
             {
                 private_handle_t* hnd =  va_arg(args, private_handle_t*);
-                bool *enable = va_arg(args, bool*);
+                uint32_t *enable = va_arg(args, uint32_t*);
                 if (private_handle_t::validate(hnd)) {
                     return res;
                 }