staging: unisys: virtpci: Remove GET_BUS_DEV macro

The GET_BUS_DEV macro contained flow control statements that are undesirable.
This patch removes the macro and places the code in each function.

Signed-off-by: Bryan Thompson <bryan.thompson@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>