Add the firmware blob required to use the sdma hardware in the imx6
processor, and its associated license text (which is similar to a
bsd-3-clause, but with a prohibition against decompiling). Install a copy
of the license in /usr/share/doc/legal/imx, to comply with the license terms
that requires a copy of the license to be delivered along with the firmware.

Obtained from: https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/imx/sdma/sdma-imx6q.bin https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/LICENSE.sdma_firmware