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/boot/Kconfig b/boot/Kconfig
index d3a12be..e581575 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -762,6 +762,13 @@
 	  booted via SD/EMMC. This is not a must, some SoCs need this,
 	  some not.
 
+config SD_BOOT_QSPI
+	bool "Support for booting from SD/EMMC and enable QSPI"
+	help
+	  Enabling this will make a U-Boot binary that is capable of being
+	  booted via SD/EMMC while enabling QSPI on the platform as well. This
+	  is not a must, some SoCs need this, some not.
+
 config SPI_BOOT
 	bool "Support for booting from SPI flash"
 	help