ofp-actions: Switch away from odd use of "q" in "enqueue" action format.
The formatting of the "enqueue" action uses a "q" to separate the port
number from the queue number, as in "enqueue:123q456". This is different
from every other action. This commit improves the situation by:
* Switching the formatting to use a colon (e.g. "enqueue:123:456"),
which is a little less odd-looking but still accepted by older
versions of Open vSwitch.
* Improving the parser to accept "enqueue(123,456)" also.
Signed-off-by: Ben Pfaff <blp@nicira.com>