LU-12942 lnet: Optimize check for routing feature flag

LU-12942 lnet: Optimize check for routing feature flag

Check the routing feature flag outside of the loop.

Cray-bug-id: LUS-7862
Test-Parameters: trivial
Signed-off-by: Chris Horn <hornc@cray.com>
Change-Id: I636305532d4bd5b8157a9df1b98af0da3bba867f
Reviewed-on: https://review.whamcloud.com/36679
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexandr Boyko <c17825@cray.com>
Reviewed-by: Alexey Lyashkov <c17817@cray.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>