mediatek: mt7622: enable support for f2fs overlay

f2fs filesystem and loop device support are needed for f2fs
overlay over squashfs.

Signed-off-by: Oskari Lemmela <oskari@lemmela.net>

target/linux/mediatek/mt7622/config-5.4

@@ -114,6 +114,7 @@ CONFIG_ARM_PMU=y
 CONFIG_ARM_PSCI_FW=y
 CONFIG_ATA=y
 CONFIG_AUDIT_ARCH_COMPAT_GENERIC=y
+CONFIG_BLK_DEV_LOOP=y
 CONFIG_BLK_DEV_SD=y
 CONFIG_BLK_MQ_PCI=y
 CONFIG_BLK_PM=y
@@ -226,6 +227,7 @@ CONFIG_DYNAMIC_DEBUG=y
 CONFIG_EDAC_SUPPORT=y
 CONFIG_EFI_EARLYCON=y
 CONFIG_EINT_MTK=y
+CONFIG_F2FS_FS=y
 CONFIG_FIXED_PHY=y
 CONFIG_FIX_EARLYCON_MEM=y
 # CONFIG_FLATMEM_MANUAL is not set