Convert CONFIG_SYS_BOOTCOUNT_LE et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_BOOTCOUNT_LE
   CONFIG_SYS_BOOTCOUNT_BE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/am335x_sl50_defconfig b/configs/am335x_sl50_defconfig
index 1338190..8808e1f 100644
--- a/configs/am335x_sl50_defconfig
+++ b/configs/am335x_sl50_defconfig
@@ -68,6 +68,7 @@
 CONFIG_NET_RETRY_COUNT=10
 CONFIG_BOOTP_SEND_HOSTNAME=y
 CONFIG_BOOTCOUNT_LIMIT=y
+CONFIG_SYS_BOOTCOUNT_BE=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SPL_SYS_I2C_LEGACY=y
 CONFIG_SYS_I2C_EEPROM_ADDR=0x50