Convert CONFIG_BOOTCOUNT_LIMIT to Kconfig

This converts the following to Kconfig:
   CONFIG_BOOTCOUNT_LIMIT

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Tested-by: Alex Kiernan <alex.kiernan@gmail.com>
Reviewed-by: Hannes Schmelzer <hannes.schmelzer@br-automation.com>
Acked-by: Hannes Schmelzer <hannes.schmelzer@br-automation.com>
diff --git a/configs/x600_defconfig b/configs/x600_defconfig
index b7d8de7..d1711e0 100644
--- a/configs/x600_defconfig
+++ b/configs/x600_defconfig
@@ -37,6 +37,7 @@
 CONFIG_MTDPARTS_DEFAULT="mtdparts=nand:64M(ubi0),64M(ubi1)"
 CONFIG_CMD_UBI=y
 CONFIG_ENV_IS_IN_FLASH=y
+CONFIG_BOOTCOUNT_LIMIT=y
 CONFIG_FPGA_XILINX=y
 CONFIG_SYS_I2C_DW=y
 # CONFIG_MMC is not set