dmaengine: sh: rz-dmac: Add device_tx_status() callback

dmaengine: sh: rz-dmac: Add device_tx_status() callback

The RZ/G2L SCIFA driver uses dmaengine_prep_slave_sg() to enqueue DMA
transfers and implements a timeout mechanism on RX to handle cases where
a DMA transfer does not complete. The timeout is implemented using an
hrtimer.

In the hrtimer callback, dmaengine_tx_status() is called (along with
dmaengine_pause()) to retrieve the transfer residue and handle incomplete
DMA transfers.

Add support for the device_tx_status() callback.

Co-developed-by: Long Luu <long.luu.ur@renesas.com>
Signed-off-by: Long Luu <long.luu.ur@renesas.com>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Co-developed-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260316133252.240348-8-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>