treewide: Convert tabs to spaces in C source files written in OVS style.

treewide: Convert tabs to spaces in C source files written in OVS style.

The Open vSwitch C style doesn't use hard tabs.

This commit doesn't touch files written in kernel style or that are
imported from other projects where we want to minimize changes from
upstream (the sflow files).

Reported-by: Mehak Mahajan <mmahajan@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>