openslug-init(modprobe.conf),nslu2.conf: generate the correct ixp-eth alias, support le

openslug-init(modprobe.conf),nslu2.conf: generate the correct ixp-eth alias, support le
modprobe.conf is now machine generated to use the PROVIDER of virtual/ixp-eth
in place of a hard code module name - PREFERRED_PROVIDER_virtual/ixp-eth must
be specified to make this work, the configuration files have been updated
appropriate.  openslug-image now pulls in virtual/ixp-eth, not a specific
provider and uses the PREFERRED_PROVIDER of that module as the RDEPENDS.
nslu2.conf and ucslugc.conf have changes to support configuration of the build
endianness correctly - not fully functional because the flash read code still
needs word swapping on LE.