mrf24j40: add tx power support
mrf24j40: add tx power support

This patch supports setting of transmit power for the mrf24j40ma
transceiver only. The mrf24j40mc has some amplifier to change the
transmit power, I am currently not sure how the mapping for this
amplifier looks like.

Signed-off-by: Alexander Aring <d03dbcdedb9639e397df9b8578e8fc8274f4e6c4@gmail.com>
Signed-off-by: Marcel Holtmann <44592b4eea36663c86b994bb0ea99d15309c1c7d@holtmann.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs