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/am335x_hs_evm_defconfig b/configs/am335x_hs_evm_defconfig
index 55565f4..b953a5c 100644
--- a/configs/am335x_hs_evm_defconfig
+++ b/configs/am335x_hs_evm_defconfig
@@ -33,6 +33,7 @@
 CONFIG_OF_CONTROL=y
 CONFIG_OF_LIST="am335x-evm am335x-bone am335x-boneblack am335x-evmsk am335x-bonegreen am335x-icev2"
 # CONFIG_BLK is not set
+CONFIG_BOOTCOUNT_LIMIT=y
 CONFIG_DFU_MMC=y
 CONFIG_DFU_NAND=y
 CONFIG_DFU_RAM=y