net/sched: fix idr leak in the error path of tcp_pedit_init()

tcf_pedit_init() can fail to allocate 'keys' after the idr has been
successfully reserved. When this happens, subsequent attempts to configure
a pedit rule using the same idr value systematically fail with -ENOSPC:

 # tc action add action pedit munge ip ttl set 63 index 100
 RTNETLINK answers: Cannot allocate memory
 We have an error talking to the kernel
 # tc action add action pedit munge ip ttl set 63 index 100
 RTNETLINK answers: No space left on device
 We have an error talking to the kernel
 # tc action add action pedit munge ip ttl set 63 index 100
 RTNETLINK answers: No space left on device
 We have an error talking to the kernel
 ...

Fix this in the error path of tcf_act_pedit_init(), calling
tcf_idr_release() in place of tcf_idr_cleanup().

Fixes: 65a206c0

 ("net/sched: Change act_api and act_xxx modules to use IDR")
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>