gianfar: Call gfar_halt_nodisable() from gfar_halt().

gfar_halt() was factored out into halting and disabling by commit
d87eb127, as the suspend() method
only wants to do the former.  However, the call to gfar_halt_nodisable()
from gfar_halt() apparently got lost during the patch respin process.

This adds it back.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>