mlx5: Use proper logging and tracing line terminations

netdev_err should use newline termination but mlx5_health_report
is used in a trace output function devlink_health_report where
no newline should be used.

Remove the newlines from a couple formats and add a format string
of "%s\n" to the netdev_err call to not directly output the
logging string.

Also use snprintf to avoid any possible output string overrun.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>