etf: Don't use BIT() in UAPI headers.

The BIT() macro isn't exported as part of the UAPI interface. So, the
compile-test to ensure they are self contained fails. So, use _BITUL()
instead.

Signed-off-by: Vedang Patel <vedang.patel@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>