fib_rules: revert the fib_rules change for vts [1/1]

fib_rules: revert the fib_rules change for vts [1/1]

PD#SWPL-9771

Problem:
The fib_rules change was incorrect and will be reverted upstream soon.

Solution:
Drop it now so that devices start working again.
Revert "fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied"
Revert "fib_rules: fix error in backport of e9919a24d302 ("fib_rules: return 0...")"
This reverts commit d5c71a7c533e88a9fcc74fe1b5c25743868fa300.
This reverts commit 1fff19a925e524556e85efcd728efad5274ce5b6

Verify:
locally

Change-Id: Iff9425390eb9a1cf2ae5d4ec4db6504c9d77de1d
Signed-off-by: jie.yuan <jie.yuan@amlogic.com>