test: cast VA_STATSUS_ERROR_UNKNOWN to VAStatus

This fixes a gcc10 compiler error for the
VA_STATUS_ERROR_UNKNOWN 0xFFFFFFFF conversion from
unsigned int to int.

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>

Author: uartie

test/test.h

@@ -147,7 +147,7 @@ class VaapiStatus
             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";