mediatek/filogic: enable mtd virtual concat support

This is required for upcoming Keenetic KN-3911 support

Signed-off-by: Maxim Anisimov <[email protected]>
Link: openwrt/openwrt#16830
Signed-off-by: Hauke Mehrtens <[email protected]>

Author: Linaro1985

target/linux/mediatek/filogic/config-6.6

@@ -269,6 +269,7 @@ CONFIG_MTD_UBI_BLOCK=y
 CONFIG_MTD_UBI_FASTMAP=y
 CONFIG_MTD_UBI_NVMEM=y
 CONFIG_MTD_UBI_WL_THRESHOLD=4096
+CONFIG_MTD_VIRT_CONCAT=y
 # CONFIG_MTK_CMDQ is not set
 CONFIG_MTK_CPUX_TIMER=y
 # CONFIG_MTK_CQDMA is not set