enic: fix UDP rss bits

In commit 48398b6e

 ("enic: set UDP rss flag") driver needed to set a
single bit to enable UDP rss. This is changed to two bit. One for UDP
IPv4 and other bit for UDP IPv6. The hardware which supports this is not
released yet. When released, driver should set 2 bit to enable UDP rss for
both IPv4 and IPv6.

Also add spinlock around vnic_dev_capable_rss_hash_type().

Signed-off-by: Govindarajulu Varadarajan <gvaradar@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>