uboot-imx

bootcount: Add bootcount command

Add a command to manipulate the bootcounter. This is useful if you can
run device recovery from inside U-Boot and need to reset the bootcounter
after executing that process as part of altbootcmd.

Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>