staging: vc04_services: parse_rx_slots() - Fix compiler warning

vc04_services contains a debug logging mechanism.  The log is
maintained in a shared memory area between the kernel and the
firmware.  Changing the sizes of the data in this area would
require a firmware change which is distributed independently
from the kernel binary.

One of the items logged is the address of received messages.
This address is a pointer, but the debugging slot used to store
the information is a 32 bit integer.

Luckily, this value is never interpreted by anything other
then debug tools and it is expected that a human debugging
the kernel interpret it.

This change adds a cast to long before the original cast
to int to silence the warning.

Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>