datapath: Use a single attribute array for parsing values and masks.

datapath: Use a single attribute array for parsing values and masks.

When parsing flow Netlink messages we currently have arrays to hold the
attribute pointers for both values and masks. This results in a large
stack, which some compilers warn about. It's not actually necessary
to have both arrays at the same time, so we can collapse this to a
single array.

Reported-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>