tty: sunsu: Simplify device_node cleanup by using __free

tty: sunsu: Simplify device_node cleanup by using __free

Add `__free` function attribute to `ap` and `match` pointer
initialisations which ensure that the pointers are freed as soon as they
go out of scope, thus removing the need to manually free them using
`of_node_put`.

This also removes the need for the `goto` statement and the `rc`
variable.

Suggested-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Shresth Prasad <shresthprasad7@gmail.com>
Link: https://lore.kernel.org/r/20240518114051.18125-3-shresthprasad7@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>