Convert CONFIG_SPL_NAND_LOAD et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SPL_NAND_LOAD
   CONFIG_SYS_NAND_BLOCK_SIZE
   CONFIG_SYS_NAND_PAGE_SIZE
   CONFIG_SYS_NAND_OOBSIZE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/am43xx_evm_rtconly_defconfig b/configs/am43xx_evm_rtconly_defconfig
index a4450cc..c1ef598 100644
--- a/configs/am43xx_evm_rtconly_defconfig
+++ b/configs/am43xx_evm_rtconly_defconfig
@@ -47,6 +47,9 @@
 CONFIG_MMC_OMAP_HS=y
 CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y
+CONFIG_SYS_NAND_BLOCK_SIZE=0x40000
+CONFIG_SYS_NAND_PAGE_SIZE=0x1000
+CONFIG_SYS_NAND_OOBSIZE=0xe0
 CONFIG_SF_DEFAULT_SPEED=48000000
 CONFIG_SPI_FLASH_MACRONIX=y
 CONFIG_PHY_GIGE=y