i3c: master: svc: Use readsb helper for reading MDB

The target can send the MDB byte followed by additional data bytes.
The readl on MRDATAB reads one actual byte, but the readsl advances
the destination pointer by 4 bytes. This causes the subsequent payload
to be copied to wrong position in the destination buffer.

Cc: stable@kernel.org
Fixes: dd3c528 ("i3c: master: svc: Add Silvaco I3C master driver")
Signed-off-by: Stanley Chu <yschu@nuvoton.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250318053606.3087121-3-yschu@nuvoton.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: stanleychuys

drivers/i3c/master/svc-i3c-master.c

@@ -425,7 +425,7 @@ static int svc_i3c_master_handle_ibi(struct svc_i3c_master *master,
 	       slot->len < SVC_I3C_FIFO_SIZE) {
 		mdatactrl = readl(master->regs + SVC_I3C_MDATACTRL);
 		count = SVC_I3C_MDATACTRL_RXCOUNT(mdatactrl);
-		readsl(master->regs + SVC_I3C_MRDATAB, buf, count);
+		readsb(master->regs + SVC_I3C_MRDATAB, buf, count);
 		slot->len += count;
 		buf += count;
 	}