Udev rules: use non-ancient comma syntax

This file is old as dirt. It's entirely possible that commas were
optional in udev back at that time. But they're definitely supposed to
be there nowadays.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302