selftests: can: test_raw_filter.sh: add support of physical interfaces

Allow the user to specify a physical interface through the $CANIF
environment variable. Add a $BITRATE environment variable set with a
default value of 500000.

If $CANIF is omitted or if it starts with vcan (e.g. vcan1), the test
will use the virtual can interface type. Otherwise, it will assume
that the provided interface is a physical can interface.

For example:

CANIF=can1 BITRATE=1000000 ./test_raw_filter.sh

will run set the can1 interface with a bitrate of one million and run
the tests on it.

Signed-off-by: Vincent Mailhol <[e-mail]>
Signed-off-by: Marc Kleine-Budde <[e-mail]>

tools/testing/selftests/net/can/test_raw_filter.sh

···
 source $net_dir/lib.sh
 
 export CANIF=${CANIF:-"vcan0"}
+BITRATE=${BITRATE:-500000}
 
 setup()
 {
-	ip link add name $CANIF type vcan || exit $ksft_skip
+	if [[ $CANIF == vcan* ]]; then
+		ip link add name $CANIF type vcan || exit $ksft_skip
+	else
+		ip link set dev $CANIF type can bitrate $BITRATE || exit $ksft_skip
+	fi
 	ip link set dev $CANIF up
 	pwd
 }
 
 cleanup()
 {
-	ip link delete $CANIF
+	ip link set dev $CANIF down
+	if [[ $CANIF == vcan* ]]; then
+		ip link delete $CANIF
+	fi
 }
 
 test_raw_filter()