ideapad: Change the driver name to ideapad-laptop

Since the platform drivers doing more for laptops than just using specific
ACPI device. It will be good to change the name from *_acpi to *-laptop.

Reference: http://lkml.org/lkml/2010/8/14/154



Signed-off-by: Ike Panhc <ike.pan@canonical.com>
Acked-by: Len Brown <len.brown@intel.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>