bnx2x: lower verbosity of VF stats debug messages

When BNX2X_MSG_IOV is enabled, the driver produces too many VF statistics
messages. Lower the verbosity of the VF stats messages similarly as in
commit 76ca70fa ("bnx2x: [Debug] change verbosity of some prints").

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>