Convert CONFIG_SD_BOOT et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SD_BOOT
   CONFIG_SD_BOOT_QSPI

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ls1046aqds_sdcard_qspi_defconfig b/configs/ls1046aqds_sdcard_qspi_defconfig
index cd7d180..c8015f4 100644
--- a/configs/ls1046aqds_sdcard_qspi_defconfig
+++ b/configs/ls1046aqds_sdcard_qspi_defconfig
@@ -26,11 +26,11 @@
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT_VERBOSE=y
 CONFIG_OF_BOARD_SETUP=y
-CONFIG_SYS_EXTRA_OPTIONS="SD_BOOT_QSPI"
 CONFIG_RAMBOOT_PBL=y
 CONFIG_SYS_FSL_PBL_PBI="board/freescale/ls1046aqds/ls1046aqds_pbi.cfg"
 CONFIG_SYS_FSL_PBL_RCW="board/freescale/ls1046aqds/ls1046aqds_rcw_sd_qspi.cfg"
 CONFIG_SD_BOOT=y
+CONFIG_SD_BOOT_QSPI=y
 CONFIG_BOOTDELAY=10
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0500 mtdparts=1550000.spi-0:2m(uboot),14m(free)"