firmware: ti_sci: rm: Add support for extended_ch_type for tx channel

Sysfw added 'extended_ch_type' to the tx_ch_cfg_req message which should be
used when BCDMA block copy channels are configured:
extended_ch_type = 0 : the channel is split tx channel (tchan)
extended_ch_type = 1 : the channel is block copy channel (bchan)

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>