Revert "SW - SIM808 Ser RX DMA - unreliable data transfer - to be reverted to IRQ variant"
Revert "SW - SIM808 Ser RX DMA - unreliable data transfer - to be reverted to IRQ variant"

This reverts commit 28d0568286bbb5d2b08c0a0a167effc4865ec433.

DF4IAH/FindMeSAT,DF4IAH/FindMeSAT,DF4IAH/FindMeSAT,DF4IAH/FindMeSAT,DF4IAH/FindMeSAT,DF4IAH/FindMeSAT