Add support for MRL B devices

[menschel]

This patch adds support for MRL B devices by masking the right most nibble when the chip is identified at start of main loop.

MRL B devices are identified by having a 1 in the right most nibble of CHIPID_CIDR.

Without masking that nibble during compare, usamba fails with an error message when an MRL B device is connected.

I took the liberty to also update the file headers to include

SPDX-License-Identifier: GPL-2.0

I hope that's fine.