LU-2084 lnet: don't retry allocating router buffers

Don't loop indefinitely trying to allocate router buffer pools if
the number of requested buffers is too large for the system.

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Ic0f2ccf0f7b38dfa254e46e268b27092342efdb5
Reviewed-on: https://review.whamcloud.com/45174
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>