Revert "Use 'ip link' to get different kinds of interfaces"

This reverts commit 8febe0e40650983d809abaa10be983bc1953ef1e.

The netlink support for bridge is only available on kernel 3.0+.
Please see the following commit for details.
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bb900b27a2f49b37bc38c08e656ea13048fee13b

Add netlink support for bond is also added after kernel 2.6.32.
So this solution doesn't work on RHEL6 system. We have to revert
it.

Change-Id: I9d3f037a9e837fd97cb8808b7bf4b72026ec77c5
Signed-off-by: Mark Wu <wudxw@linux.vnet.ibm.com>
Reviewed-on: http://gerrit.ovirt.org/14157
Reviewed-by: Dan Kenigsberg <danken@redhat.com>