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/ls2080aqds_nand_defconfig b/configs/ls2080aqds_nand_defconfig
index 3976284..90e4a22 100644
--- a/configs/ls2080aqds_nand_defconfig
+++ b/configs/ls2080aqds_nand_defconfig
@@ -61,6 +61,7 @@
 CONFIG_SYS_I2C_EEPROM_ADDR=0x57
 CONFIG_FSL_ESDHC=y
 CONFIG_MTD=y
+CONFIG_SYS_NAND_BLOCK_SIZE=0x20000
 CONFIG_DM_SPI_FLASH=y
 # CONFIG_SPI_FLASH_BAR is not set
 CONFIG_PHYLIB=y