staging: comedi: adl_pci7x3x: fix pointer-to-int-cast warning

This driver uses the void *private variable in the comedi_subdevice
to pass the offset needed to read/write the appropriate register to
get/set the channels for the subdevice.

The adl_pci7x3x_do_insn_bits() and adl_pci7x3x_di_insn_bits() functions
were retrieving this offset by casting the s->private value as an
unsigned int. On 64-bit builds this results in a warning:

warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]

Fix these warnings by casting the void * to an unsigned long.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>