tests: move stderr redirection out from test expression

Fix shellcheck error.

if ! [ "$paraller_jobs" -ge 0 2>/dev/null ]; then
^-- SC1009: The mentioned parser error was in this if expression.
     ^-- SC1073: Couldn't parse this test expression.
                              ^-- SC1072: Expected test to end here (don't
                                  wrap commands in []/[[]]). Fix any
                                  mentioned problems and try again.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

tests/run.sh

@@ -82,7 +82,7 @@ while [ -n "$1" ]; do
 		;;
 	--parallel=*)
 		paraller_jobs="${1##--parallel=}"
-		if ! [ "$paraller_jobs" -ge 0 2>/dev/null ]; then
+		if ! [ "$paraller_jobs" -ge 0 ] 2>/dev/null; then
 			echo "invalid argument '$paraller_jobs' for --parallel="
 			exit 1
 		fi