realtek: Enhance MTD/ECC kernel configuration for NAND targets

The Realtek NAND kernel configuration has some shortcomings.
Fix this as follows:

- MTD_NAND_ECC_REALTEK selects MTD_NAND_ECC and this selects
  MTD_NAND_CORE. For consistency add both config options.

- The partition layout of the Linksys switches requires some tricky
  concatenation to keep dual boot active. Add CONFIG_MTD_VIRT_CONCAT

Signed-off-by: Markus Stockhausen <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20255
Signed-off-by: Robert Marko <[email protected]>

target/linux/realtek/rtl930x_nand/config-6.12

@@ -145,6 +145,8 @@ CONFIG_MTD_CFI_ADV_OPTIONS=y
 CONFIG_MTD_CFI_GEOMETRY=y
 CONFIG_MTD_CMDLINE_PARTS=y
 CONFIG_MTD_JEDECPROBE=y
+CONFIG_MTD_NAND_CORE=y
+CONFIG_MTD_NAND_ECC=y
 CONFIG_MTD_NAND_ECC_REALTEK=y
 CONFIG_MTD_SPI_NAND=y
 CONFIG_MTD_SPI_NOR=y
@@ -157,6 +159,7 @@ CONFIG_MTD_UBI=y
 CONFIG_MTD_UBI_BEB_LIMIT=20
 CONFIG_MTD_UBI_BLOCK=y
 CONFIG_MTD_UBI_WL_THRESHOLD=4096
+CONFIG_MTD_VIRT_CONCAT=y
 CONFIG_NEED_DMA_MAP_STATE=y
 CONFIG_NEED_PER_CPU_KM=y
 CONFIG_NET_DEVLINK=y

target/linux/realtek/rtl931x_nand/config-6.12

@@ -156,6 +156,8 @@ CONFIG_MTD_CFI_ADV_OPTIONS=y
 CONFIG_MTD_CFI_GEOMETRY=y
 CONFIG_MTD_CMDLINE_PARTS=y
 CONFIG_MTD_JEDECPROBE=y
+CONFIG_MTD_NAND_CORE=y
+CONFIG_MTD_NAND_ECC=y
 CONFIG_MTD_NAND_ECC_REALTEK=y
 CONFIG_MTD_SPI_NAND=y
 CONFIG_MTD_SPI_NOR=y
@@ -168,6 +170,7 @@ CONFIG_MTD_UBI=y
 CONFIG_MTD_UBI_BEB_LIMIT=20
 CONFIG_MTD_UBI_BLOCK=y
 CONFIG_MTD_UBI_WL_THRESHOLD=4096
+CONFIG_MTD_VIRT_CONCAT=y
 CONFIG_NEED_DMA_MAP_STATE=y
 CONFIG_NEED_SRCU_NMI_SAFE=y
 CONFIG_NET_DEVLINK=y