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/P1010RDB-PA_NOR_defconfig b/configs/P1010RDB-PA_NOR_defconfig
index 89fccd6..982da33 100644
--- a/configs/P1010RDB-PA_NOR_defconfig
+++ b/configs/P1010RDB-PA_NOR_defconfig
@@ -66,6 +66,7 @@
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_FLASH_CFI_DRIVER=y
 CONFIG_SYS_FLASH_USE_BUFFER_WRITE=y
+CONFIG_SYS_FLASH_EMPTY_INFO=y
 CONFIG_SYS_FLASH_CFI=y
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SF_DEFAULT_SPEED=10000000