LU-16518 lnet: fix uninitialized variable in api-ni.c

LU-16518 lnet: fix uninitialized variable in api-ni.c

Fix new Clang error in api-ni.c:

 warning: variable 'lpni' is used uninitialized whenever
 'if' condition is false [-Wsometimes-uninitialized]

Fixes: f0be006 ("LU-9680 lnet: collect data about peer_ni by using Netlink")
Test-Parameters: trivial testlist=sanity-lnet
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I0895f02aaeb4fbb3b40a6927e77b8f02cfb3bfe8
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53174
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>