bcm53xx: switch RT-N18U firmware to the UBI

According to the ticket #18152 it also uses NAND with 0x20000 erase size
and 0x800 page size.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

SVN-Revision: 43008

target/linux/bcm53xx/image/Makefile

@@ -81,7 +81,7 @@ endef
 define Image/Build
 	( cd $(KDIR); $(STAGING_DIR_HOST)/bin/ubinize -p 128KiB -m 2048 -o $(KDIR)/root-block-0x20000-min-0x800.ubi ubinize.cfg )
 
-	$(call Image/Build/AsusTrx,$(1),bcm47081-asus-rt-n18u,serial,RT-N18U)
+	$(call Image/Build/AsusTrx,$(1),bcm47081-asus-rt-n18u,nand-0x20000-0x800,RT-N18U)
 
 	$(call Image/Build/Chk,$(1),bcm4708-netgear-r6250,nand-0x20000-0x800,U12H245T00_NETGEAR,1)
 	$(call Image/Build/Chk,$(1),bcm4708-netgear-r6300-v2,nand-0x20000-0x800,U12H240T00_NETGEAR,1)