icside: use ide_init_port_hw()

* Move ide_find_port() and default_hwif_mmiops() calls from icside_setup()
  to icside_register_v{5,6}().

* Convert icside_setup() to initialize hw_regs_t instead ide_hwif_t
  and icside_register_v{5,6}() to use ide_init_port_hw().

* Rename icside_setup() to icside_setup_ports().

There should be no functional changes caused by this patch.

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