icside: always try to probe first interface

Try to probe first interface even if ide_hwifs[]'s slot for the second
interface cannot be obtained.

While at it:

- Add DRV_NAME define and use it for request_dma() instead of hwif->name.

Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>