imgtec: Update MAINTAINERS for more config files

Cover all of the boston and malta variations.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/imgtec/boston/MAINTAINERS b/board/imgtec/boston/MAINTAINERS
index 30dd481..ec850d2 100644
--- a/board/imgtec/boston/MAINTAINERS
+++ b/board/imgtec/boston/MAINTAINERS
@@ -3,4 +3,7 @@
 S:	Maintained
 F:	board/imgtec/boston/
 F:	include/configs/boston.h
-F:	configs/boston_defconfig
+F:	configs/boston32r2_defconfig
+F:	configs/boston32r2el_defconfig
+F:	configs/boston64r2_defconfig
+F:	configs/boston64r2el_defconfig