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/maltael_defconfig b/configs/maltael_defconfig
index e268fb6..ef31afe 100644
--- a/configs/maltael_defconfig
+++ b/configs/maltael_defconfig
@@ -39,6 +39,7 @@
 CONFIG_FLASH_CFI_DRIVER=y
 CONFIG_SYS_FLASH_USE_BUFFER_WRITE=y
 CONFIG_SYS_FLASH_CFI=y
+CONFIG_SYS_MAX_FLASH_SECT=128
 CONFIG_PCNET=y
 CONFIG_PCI_GT64120=y
 CONFIG_PCI_MSC01=y