ahci-plat: provide a weak scsi_bus_reset() hook

This allow the platform to handle a custom reset sequence.

Signed-off-by: Dmitry Lifshitz <lifshitz@compulab.co.il>
Reviewed-by: Tom Rini <trini@ti.com>

drivers/block/ahci.c

@@ -1010,12 +1010,11 @@ static int ata_io_flush(u8 port)
 }
 
 
-void scsi_bus_reset(void)
+__weak void scsi_bus_reset(void)
 {
 	/*Not implement*/
 }
 
-
 void scsi_print_error(ccb * pccb)
 {
 	/*The ahci error info can be read in the ahci driver*/