Revert "OP-1532 fix non-ppm mode"

This reverts commit 9fd4fb26b9dde4d9e29c4be19bcee98de695af04.
Revert "OP-1530 Use rfm22b_dev->num_channels"

This reverts commit 4e365f6dffc2c0776e0d7efdf9e697d1a21c4047.
Revert "OP-1522 Robustness of OPLink radio"

This reverts commit 00d9c668677cc0d6ae453651d27f30a445e0a1f8.