test: cast VA_STATUS_ERROR_UNKNOWN to VAStatus type

This fixes a GCC 10.0.1 compiler error for the
VA_STATUS_ERROR_UNKNOWN 0xFFFFFFFF conversion from
unsigned to int.

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>
diff --git a/test/test.h b/test/test.h
index a1a86f5..a2ad997 100644
--- a/test/test.h
+++ b/test/test.h
@@ -142,7 +142,7 @@
             status = "VA_STATUS_ERROR_HW_BUSY"; break;
         case VA_STATUS_ERROR_UNSUPPORTED_MEMORY_TYPE:
             status = "VA_STATUS_ERROR_UNSUPPORTED_MEMORY_TYPE"; break;
-        case VA_STATUS_ERROR_UNKNOWN:
+        case VAStatus(VA_STATUS_ERROR_UNKNOWN):
             status = "VA_STATUS_ERROR_UNKNOWN"; break;
         default:
             status = "Unknown VAStatus";