Cleanup: Go with SkDebugf instead of GrPrintf.

Since GrPrintf is just defined to SkDebugf, we can go with the later
directly.

BUG=None
TEST=None
R=bsalomon@google.com

Review URL: https://codereview.chromium.org/695663003
diff --git a/src/gpu/GrGpuFactory.cpp b/src/gpu/GrGpuFactory.cpp
index 16405b4..6397bb2 100644
--- a/src/gpu/GrGpuFactory.cpp
+++ b/src/gpu/GrGpuFactory.cpp
@@ -30,7 +30,7 @@
         }
         if (NULL == glInterface) {
 #ifdef SK_DEBUG
-            GrPrintf("No GL interface provided!\n");
+            SkDebugf("No GL interface provided!\n");
 #endif
             return NULL;
         }