sata_highbank: Rename proc_name to the module name

mkinitrd looks at /sys/class/scsi_host/host$hostnum/proc_name to find
the module name of a disk driver. Current name is "highbank-ahci" but
the module is "sata_highbank". Rename it to match the module name.

Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Alexander Graf <agraf@suse.de>
Cc: <stable@vger.kernel.org> v3.7..
Signed-off-by: Robert Richter <robert.richter@calxeda.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>