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/pg_wcom_seli8_defconfig b/configs/pg_wcom_seli8_defconfig
index a604d32..ae67996 100644
--- a/configs/pg_wcom_seli8_defconfig
+++ b/configs/pg_wcom_seli8_defconfig
@@ -81,6 +81,7 @@
 CONFIG_FLASH_CFI_DRIVER=y
 CONFIG_CFI_FLASH_USE_WEAK_ACCESSORS=y
 CONFIG_SYS_FLASH_USE_BUFFER_WRITE=y
+CONFIG_SYS_FLASH_EMPTY_INFO=y
 CONFIG_FLASH_CFI_MTD=y
 CONFIG_SYS_FLASH_CFI=y
 CONFIG_MTD_RAW_NAND=y