Convert CONFIG_SYS_FLASH_EMPTY_INFO to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_FLASH_EMPTY_INFO

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/integratorcp_cm920t_defconfig b/configs/integratorcp_cm920t_defconfig
index d895ba4..eb9d1b7 100644
--- a/configs/integratorcp_cm920t_defconfig
+++ b/configs/integratorcp_cm920t_defconfig
@@ -33,6 +33,7 @@
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_FLASH_CFI_DRIVER=y
+CONFIG_SYS_FLASH_EMPTY_INFO=y
 CONFIG_SYS_FLASH_PROTECTION=y
 CONFIG_SYS_FLASH_CFI=y
 CONFIG_BAUDRATE=38400