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/configs/socrates_defconfig b/configs/socrates_defconfig
index 60a38ab..75195b3 100644
--- a/configs/socrates_defconfig
+++ b/configs/socrates_defconfig
@@ -73,6 +73,7 @@
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_FLASH_CFI_DRIVER=y
 CONFIG_SYS_FLASH_CFI=y
+CONFIG_SYS_MAX_FLASH_SECT=256
 CONFIG_SYS_MAX_FLASH_BANKS=2
 CONFIG_MTD_RAW_NAND=y
 CONFIG_PHY_ATHEROS=y