test: system: Return memory size rather than mtd size in LPC ioctl

The old behaviour was an outright bug in the system framework. The size
of the LPC reserved memory window has nothing to do with the size of the
flash.

Change-Id: Ie16686ac6df8fb3117fb46aa2eaab082873fd4d0
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/test/system.c b/test/system.c
index 3b5a9bd..2068fb9 100644
--- a/test/system.c
+++ b/test/system.c
@@ -90,7 +90,7 @@
 
 		va_start(ap, request);
 		info = va_arg(ap, struct aspeed_lpc_ctrl_mapping *);
-		info->size = mtd.size;
+		info->size = ctrl.size;
 		va_end(ap);
 		break;
 	}