at91: Switch to SD_BOOT / CONFIG_NAND_BOOT

The values CONFIG_SYS_USE_NANDFLASH and CONFIG_SYS_USE_MMC serve the
same purpose as CONFIG_SD_BOOT / CONFIG_NAND_BOOT so migrate to using
these switches instead as they're already in Kconfig.

Cc: Stelian Pop <stelian@popies.net>
Cc: Heiko Schocher <hs@denx.de>
Cc: Daniel Gorsulowski <daniel.gorsulowski@esd.eu>
Cc: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/meesc_defconfig b/configs/meesc_defconfig
index 312c15f..40b0f13 100644
--- a/configs/meesc_defconfig
+++ b/configs/meesc_defconfig
@@ -12,7 +12,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="at91sam9263ek"
 CONFIG_SYS_LOAD_ADDR=0x20100000
 CONFIG_FIT=y
-CONFIG_SYS_EXTRA_OPTIONS="SYS_USE_NANDFLASH"
+CONFIG_NAND_BOOT=y
 CONFIG_BOOTDELAY=3
 CONFIG_USE_PREBOOT=y
 CONFIG_BOARD_EARLY_INIT_F=y
@@ -36,7 +36,6 @@
 CONFIG_AT91_GPIO=y
 # CONFIG_MMC is not set
 CONFIG_MTD=y
-CONFIG_MTD_RAW_NAND=y
 # CONFIG_SYS_NAND_USE_FLASH_BBT is not set
 CONFIG_NAND_ATMEL=y
 CONFIG_DM_SPI_FLASH=y