Convert CONFIG_SYS_MAX_FLASH_SECT to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_MAX_FLASH_SECT

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
index 431168d..828ec97 100644
--- a/drivers/mtd/Kconfig
+++ b/drivers/mtd/Kconfig
@@ -171,6 +171,11 @@
 	 This is the driver of embedded flash for some STMicroelectronics
 	 STM32 MCU.
 
+config SYS_MAX_FLASH_SECT
+	int "Maximumm number of sectors on a flash chip"
+	depends on MTD_NOR_FLASH || FLASH_CFI_DRIVER
+	default 512
+
 config SAMSUNG_ONENAND
 	bool "Samsung OneNAND driver support"