UPSTREAM: ipv4: add missing initialization for flowi4_uid

commit 8bcfd0925ef15f072ba1e7bee2c25e9e1b5fd6ca upstream.

Avoid matching of random stack value for uid when rules
are looked up on input route or when RP filter is used.
Problem should affect only setups that use ip rules with
uid range.

Fixes: 622ec2c9d524 ("net: core: add UID to flows, rules, and routes")
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>

Change-Id: I482d3e283a7515ea2d6a84920d66839341e63be5
Fixes: ("UPSTREAM: net: core: add UID to flows, rules, and routes")
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>