ARM: imx: mx5: Add altbootcmd and resets to M53Menlo

Bulletproof the default boot command with reset statements in case
any command in the chain would fail. In case a failure were to happen,
the board will reset, increment boot counter and retry the procedure.
In case the failures persist and the boot counter reaches the bootlimit,
U-Boot starts altbootcmd instead of the default bootcmd boot command.

The altbootcmd swaps the default boot partition for the other boot
partition, which is an identical copy or an older copy, and tries
booting from that one instead.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Stefano Babic <sbabic@denx.de>