usb: hub: Simplify error and success path in port_over_current_notify

kasprintf() returns NULL or valid pointer. Since kfree() can handle
NULL pointer condition, simplify error and success paths in function
port_over_current_notify() by removing multiple error path labels.

Signed-off-by: Bhuvanesh Surachari <Bhuvanesh_Surachari@mentor.com>
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Link: https://lore.kernel.org/r/1652369834-4480-1-git-send-email-erosca@de.adit-jv.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>