gralloc: Fix incorrect handle validation check

The YUV plane info reported to driver has an incorrect handle
check. Use the check correctly.

Change-Id: Ice6388a3d8b91bfa5373e850e3102c6ccf92eb75
diff --git a/libgralloc/mapper.cpp b/libgralloc/mapper.cpp
index 4adc67d..338f9db 100644
--- a/libgralloc/mapper.cpp
+++ b/libgralloc/mapper.cpp
@@ -431,7 +431,7 @@
             {
                 private_handle_t* hnd =  va_arg(args, private_handle_t*);
                 android_ycbcr* ycbcr = va_arg(args, struct android_ycbcr *);
-                if (private_handle_t::validate(hnd)) {
+                if (!private_handle_t::validate(hnd)) {
                     res = getYUVPlaneInfo(hnd, ycbcr);
                 }
             } break;