rdma: Limit copy data by the destination size

rdma: Limit copy data by the destination size

The strncat() function will copy upto n bytes supplied as third
argument. The n bytes shouldn't be no more than destination and
not the source.

This change fixes the following clang compilation warnings:

res-srq.c:75:25: warning: size argument in 'strncat' call appears to be size of the source [-Wstrncat-size]
                        strncat(qp_str, tmp, sizeof(tmp) - 1);
                                             ^~~~~~~~~~~~~~~
res-srq.c:99:23: warning: size argument in 'strncat' call appears to be size of the source [-Wstrncat-size]
        strncat(qp_str, tmp, sizeof(tmp) - 1);
                             ^~~~~~~~~~~~~~~
res-srq.c:142:25: warning: size argument in 'strncat' call appears to be size of the source [-Wstrncat-size]
                        strncat(qp_str, tmp, sizeof(tmp) - 1);
                                             ^~~~~~~~~~~~~~~

Fixes: 9b272e138d23 ("rdma: Add SRQ resource tracking information")
Reported-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David Ahern <dsahern@kernel.org>