lsxl: unset ncip for rescue mode

Instead of using the serverip we get from the DHCP server, implicitly use
the broadcast address, which is automatically set when no ncip environment
variable is set. That way it isn't necessary to use a special DHCP
configuration to set the netconsole peer.

Signed-off-by: Michael Walle <michael@walle.cc>
Cc: Prafulla Wadaskar <prafulla@marvell.com>
diff --git a/include/configs/lsxl.h b/include/configs/lsxl.h
index 8097f28..59f151a 100644
--- a/include/configs/lsxl.h
+++ b/include/configs/lsxl.h
@@ -146,7 +146,7 @@
 	"config_nc_dhcp=setenv autoload_old ${autoload}; "		\
 		"setenv autoload no "					\
 		"&& bootp "						\
-		"&& setenv ncip ${serverip} "				\
+		"&& setenv ncip "					\
 		"&& setenv autoload ${autoload_old}; "			\
 		"setenv autoload_old\0"					\
 	"standard_env=setenv ipaddr; setenv netmask; setenv serverip; "	\