nimble/ll: Set phy mode before scheduling tx
nimble/ll: Set phy mode before scheduling tx

We need to set phy mode before scheduling tx as otherwise calculations
in ble_phy will use invalid phy and can be off few usecs.

X-Original-Commit: 9dc306abccf7d5ecd13e63bb9b681aa420776a85

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble