storagefile: Rename qcow2GetBackingStoreFormat

...to qcow2GetExtensions. We will extend it for more extension
parsing in future patches
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

src/util/virstoragefile.c

@@ -427,7 +427,7 @@ cowGetBackingStore(char **res,
 
 
 static int
-qcow2GetBackingStoreFormat(int *format,
+qcow2GetExtensions(int *format,
                    const char *buf,
                    size_t buf_size)
 {
@@ -561,7 +561,7 @@ qcowXGetBackingStore(char **res,
     memcpy(*res, buf + offset, size);
     (*res)[size] = '\0';
 
-    if (qcow2GetBackingStoreFormat(format, buf, buf_size) < 0)
+    if (qcow2GetExtensions(format, buf, buf_size) < 0)
         return BACKING_STORE_INVALID;
 
     return BACKING_STORE_OK;