cgtqmx6eval: Fix defconfig name

After the conversion to SPL the defconfig was renamed, so adjust it.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>

board/congatec/cgtqmx6eval/MAINTAINERS

@@ -3,4 +3,4 @@ M:	Otavio Salvador <otavio@ossystems.com.br>
 S:	Maintained
 F:	board/congatec/cgtqmx6eval/
 F:	include/configs/cgtqmx6eval.h
-F:	configs/cgtqmx6qeval_defconfig
+F:	configs/cgtqmx6eval_defconfig