s390/tape: fix virtual vs physical address confusion

Fix virtual vs physical address confusion and use new dma types and helper
functions to allow for type checking. This does not fix a bug since virtual
and physical address spaces are currently the same.

Tested-by: Jan Höppner <[e-mail]>
Reviewed-by: Jan Höppner <[e-mail]>
Signed-off-by: Heiko Carstens <[e-mail]>

drivers/s390/char/tape.h

···
 	ccw->cmd_code = cmd_code;
 	ccw->flags = CCW_FLAG_CC;
 	ccw->count = memsize;
-	ccw->cda = (__u32)(addr_t) cda;
+	ccw->cda = 0;
+	if (cda)
+		ccw->cda = virt_to_dma32(cda);
 	return ccw + 1;
 }
 
···
 	ccw->cmd_code = cmd_code;
 	ccw->flags = 0;
 	ccw->count = memsize;
-	ccw->cda = (__u32)(addr_t) cda;
+	ccw->cda = 0;
+	if (cda)
+		ccw->cda = virt_to_dma32(cda);
 	return ccw + 1;
 }
 
···
 	ccw->cmd_code = cmd_code;
 	ccw->flags = 0;
 	ccw->count = 0;
-	ccw->cda = (__u32)(addr_t) &ccw->cmd_code;
+	ccw->cda = virt_to_dma32(&ccw->cmd_code);
 	return ccw + 1;
 }
 
···
 		ccw->cmd_code = cmd_code;
 		ccw->flags = CCW_FLAG_CC;
 		ccw->count = 0;
-		ccw->cda = (__u32)(addr_t) &ccw->cmd_code;
+		ccw->cda = virt_to_dma32(&ccw->cmd_code);
 		ccw++;
 	}
 	return ccw;