mesh: Fix using the correct transmit state
mesh: Fix using the correct transmit state

If relaying is not supported, or disabled, the Relay Transmit state
will normally be 0, which is not what we want to use when proxying out
packets from GATT clients. The bt_mesh_net_relay() function is also
used for sending out locally originated packets, in which case the
Relay Retransmit state is also the wrong one to use (the Network
Transmit state should be used instead).

This patch makes sure we only use the Relay Retransmit state for
packets originating from the advertising bearer, and for all other
packets use the Network Transmit state.

IMGJulian/incubator-mynewt-core,andrzej-kaczmarek/incubator-mynewt-core,IMGJulian/incubator-mynewt-core,andrzej-kaczmarek/apache-mynewt-core,andrzej-kaczmarek/incubator-mynewt-core,IMGJulian/incubator-mynewt-core,IMGJulian/incubator-mynewt-core,mlaz/mynewt-core,andrzej-kaczmarek/apache-mynewt-core,andrzej-kaczmarek/incubator-mynewt-core,mlaz/mynewt-core,andrzej-kaczmarek/incubator-mynewt-core,andrzej-kaczmarek/apache-mynewt-core,IMGJulian/incubator-mynewt-core,mlaz/mynewt-core,andrzej-kaczmarek/incubator-mynewt-core,mlaz/mynewt-core,andrzej-kaczmarek/apache-mynewt-core,mlaz/mynewt-core