net: sunrpc: Fix 'snprintf' return value check in 'do_xprt_debugfs'

net: sunrpc: Fix 'snprintf' return value check in 'do_xprt_debugfs'

[ Upstream commit 35a6d396721e28ba161595b0fc9e8896c00399bb ]

'snprintf' returns the number of characters which would have been written
if enough space had been available, excluding the terminating null byte.
Thus, the return value of 'sizeof(buf)' means that the last character
has been dropped.

Signed-off-by: Fedor Tokarev <ftokarev@gmail.com>
Fixes: 2f34b8bfae19 ("SUNRPC: add links for all client xprts to debugfs")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>