parport: use subsys_initcall

The drivers which depends on parport may sometimes try to iniitialize
and register with parport bus even before parport has actually
registered with the device layer.
The simplest solution is to mark the init function as subsys_initcall()
and load the parport before the other drivers loads.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>