compat: Initialize IPv4 reassembly secret timer

compat: Initialize IPv4 reassembly secret timer

The RHEL 7 kernels expect the secret timer interval to be initialized
before calling the inet_frags_init() function.  By not initializing it
the inet_frags_secret_rebuild() function was running on every tick
rather than on the expected interval.  This caused occasional panics
from page faults when inet_frags_secret_rebuild() would try to rearm a
timer from the openvswitch kernel module which had just been removed.

Also remove the prior, and now unnecessary, work around.

VMware BZ 2094203

Fixes: 595e069a ("compat: Backport IPv4 reassembly.")
Signed-off-by: Greg Rose <gvrose8192@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Yi-Hung Wei <yihung.wei@gmail.com>