vmxnet3: make bit twiddle routines inline

Gcc doesn't usually handle inline across compilation units, and the
functions don't have to be global in scope. Move the set/reset flag
functions int the existing vmxnet3 header.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Shreyas Bhatewara <sbhatewara@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>