Convert CONFIG_SYS_FSL_DDR_INTLV_256B to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_FSL_DDR_INTLV_256B

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ls2080aqds_qspi_defconfig b/configs/ls2080aqds_qspi_defconfig
index 6bb3781..d2dd95e 100644
--- a/configs/ls2080aqds_qspi_defconfig
+++ b/configs/ls2080aqds_qspi_defconfig
@@ -60,6 +60,7 @@
 CONFIG_DIMM_SLOTS_PER_CTLR=2
 CONFIG_DDR_ECC=y
 CONFIG_ECC_INIT_VIA_DDRCONTROLLER=y
+CONFIG_SYS_FSL_DDR_INTLV_256B=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SYS_I2C_EARLY_INIT=y
 CONFIG_SYS_I2C_EEPROM_ADDR=0x57