nx-match: Speak of 'class' instead of 'vendor' for OXM/NXM.

OXM renamed the 'vendor' field from NXM to the 'class', and uses the term
"experimenter", which OVS usually renders as "vendor" for historical
reasons, as part of the extended 64-bit OXMs.  To reduce confusion, this
commit adopts the OXM terminology for class.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
util: Make hexits_value() support 64-bit integers too.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>