virt: vbox: use %pap format for printing resource_size_t

resource_size_t may be larger than pointers depending on configuration,
so we can run into this build warning:

drivers/virt/vboxguest/vboxguest_linux.c: In function 'vbg_pci_probe':
drivers/virt/vboxguest/vboxguest_linux.c:295:4: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
drivers/virt/vboxguest/vboxguest_linux.c:367:4: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]

This uses the special %pap to print the address by reference.

Fixes: 0ba002bc ("virt: Add vboxguest driver for Virtual Box Guest integration")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>