bridge: Always call smap_destroy() after smap_init()

bridge: Always call smap_destroy() after smap_init()

This commit fixes a place in bridge.c where smap_destroy() is not
always called after smap_init().  Though there is no memory leak
now, it is necessary to fix it and prevent memory leak in the
future when smap_init() may be modified to allocate dynamic memory.

Reported-by: Ansis Atteka <aatteka@nicira.com>
Signed-off-by: Alex Wang <alexw@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>