staging/slicoss: Use ether_crc for mac hash calculation

Instead of performing the hash calculation for the mac address by ourself, we
can simply reuse ether_crc and shift only the result according to our
needs.
The code was tested against the previous implementation by verifying both
implementations against each other in userspace for 16200000000 different
mac addresses, changing the vendor bits of the mac address first.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>