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/blanche_defconfig b/configs/blanche_defconfig
index 42f3dc4..8167dd1 100644
--- a/configs/blanche_defconfig
+++ b/configs/blanche_defconfig
@@ -60,6 +60,7 @@
 CONFIG_SYS_FLASH_CFI_WIDTH_16BIT=y
 CONFIG_CFI_FLASH_USE_WEAK_ACCESSORS=y
 CONFIG_SYS_FLASH_CFI=y
+CONFIG_SYS_MAX_FLASH_SECT=1024
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_SMC911X=y