libhsakmt: Move global zfb_support to globals.c

zfb_support needs to accessed from multiple places, so move to globals.c
file

Change-Id: I40b487c26a13e7cc6fc01b671d6166e7114e02d2
Signed-off-by: Harish Kasiviswanathan <Harish.Kasiviswanathan@amd.com>

src/globals.c

@@ -37,3 +37,5 @@ int PAGE_SHIFT;
 
 /* whether to check all dGPUs in the topology support SVM API */
 bool is_svm_api_supported;
+/* zfb is mainly used during emulation */
+int zfb_support;