ipv4: fib_semantics: increment fib_info_cnt after fib_info allocation

ipv4: fib_semantics: increment fib_info_cnt after fib_info allocation

[ Upstream commit aeefa1ecfc799b0ea2c4979617f14cecd5cccbfd ]

Increment fib_info_cnt in fib_create_info() right after successfuly
alllocating fib_info structure, overwise fib_metrics allocation failure
leads to fib_info_cnt incorrectly decremented in free_fib_info(), called
on error path from fib_create_info().

Signed-off-by: Sergey Popovich <popovich_sergei@mail.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>