Fix two problems:

• In subr_ndis.c:ndis_allocate_sharemem(), create the busdma tags used for shared memory allocations with a lowaddr of 0x3E7FFFFF. This forces the buffers to be mapped to physical/bus addresses within the first 1GB of physical memory. It seems that at least one card (Linksys Instant Wireless PCI V2.7) depends on this behavior. I don't know if this is a hardware restriction, or if the NDIS driver for this card is truncating the addresses itself, but using physical/bus addresses beyong the 1GB limit causes initialization failures.

• Create am NDIS_INITIALIZED() macro in if_ndisvar.h and use it in if_ndis.c to test whether the device has been initialized rather than checking for the presence of the IFF_UP flag in if_flags. While debugging the previous problem, I noticed that bringing up the device would always produce failures from ndis_setmulti(). It turns out that the following steps now occur during device initialization:

• IFF_UP flag is set in if_flags
• ifp->if_ioctl() called with SIOCSIFADDR (which we don't handle)
• ifp->if_ioctl() called with SIOCADDMULTI
• ifp->if_ioctl() called with SIOCADDMULTI (again)
• ifp->if_ioctl() called with SIOCADDMULTI (yet again)
• ifp->if_ioctl() called with SIOCSIFFLAGS
  
  Setting the receive filter and multicast filters can only be done when the underlying NDIS driver has been initialized, which is done by ifp->if_init(). However, we don't call ifp->if_init() until ifp->if_ioctl() is called with SIOCSIFFLAGS and IFF_UP has been set. It appears that now, the network stack tries to add multicast addresses to interface's filter before those steps occur. Normally, ndis_setmulti() would trap this condition by checking for the IFF_UP flag, but the network code has in fact set this flag already, so ndis_setmulti() is fooled into thinking the interface has been initialized when it really hasn't.
  
  It turns out this is usually harmless because the ifp->if_init() routine (in this case ndis_init()) will set up the multicast filter when it initializes the hardware anyway, and the underlying routines (ndis_get_info()/ndis_set_info()) know that the driver/NIC haven't been initialized yet, but you end up spurious error messages on the console all the time.

Something tells me this new behavior isn't really correct. I think
the intention was to fix it so that ifp->if_init() is only called
once when we ifconfig an interface up, but the end result seems a
little bogus: the change of the IFF_UP flag should be propagated
down to the driver before calling any other ioctl() that might actually
require the hardware to be up and running.