bridge: Refresh STP statistics separately from status

Currently, we refresh STP status (id, state, role) alongside
statistics (rx, tx, errors), all within instant_stats_run(). This
patch splits statistics out, and refreshes them with the 5 second
stats instead. This paves the way to reducing execution of
instant_stats_run().

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
util: Fix sparse warning.

Without this commit, sparse warns:

    lib/util.c:921:15: warning: symbol 'count_1bits_8' was not declared.
    Should it be static?

Introduced by commit c3cc4d2dd2658 (util: Better count_1bits().).

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>