fm10k/base: fix VF multicast

fm10k/base: fix VF multicast

The VF will send a message to request multicast addresses with the
default vid. In the current code, if the PF has statically assigned a
VLAN to a VF, then the VF will not get the multicast addresses. Fix up
all of the various vlan messages to use identical checks (since each
check was different). Also use set as a variable, so that it simplifies
our check for whether vlan matches the pf_vid.

The new logic will allow set of a vlan if it is zero, automatically
converting to the default vid. Otherwise it will allow setting the PF
vid, or any VLAN if PF has not statically assigned a VLAN. This is
consistent behavior, and allows VF to request either 0 or the
default_vid without silently failing. Note that we need the check for
zero since VFs might not get the default VID message in time to actually
request non-zero VLANs.

Create a function, fm10k_iov_select_vid which implements the logic for
selecting a default vid. This helps us remove duplicate code and
streamlines location of this logic so that we don't make similar bugs in
the future.

Signed-off-by: Wang Xiao W <xiao.w.wang@intel.com>