cxgb4: Fix unintentional sign extension issues

The shifting of the u8 integers f->fs.nat_lip[] by 24 bits to
the left will be promoted to a 32 bit signed int and then
sign-extended to a u64. In the event that the top bit of the u8
is set then all then all the upper 32 bits of the u64 end up as
also being set because of the sign-extension. Fix this by
casting the u8 values to a u64 before the 24 bit left shift.

Addresses-Coverity: ("Unintended sign extension")
Fixes: 12b276fb

 ("cxgb4: add support to create hash filters")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>