USB: typec: tcpm: no need to check return value of debugfs_create_dir()

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Clean up the tcpm.c code to not care about this, turns out no one was
even checking the return value of this function, so it didn't matter.

Note, I do not think this code can be removed in a running system, as
the debugfs root directory will stick around, that should be fixed
someday...

Revieved-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>