reset: Remove copy'n'paste redundancy in the comments

It seems the commit bb475230b8e5
("reset: make optional functions really optional")
brought couple of redundant lines in the comments.

Drop them here.

Cc: Ramiro Oliveira <[e-mail]>
Signed-off-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Philipp Zabel <[e-mail]>

drivers/reset/core.c

···
  * internal state to be reset, but must be prepared for this to happen.
  * Consumers must not use reset_control_reset on shared reset lines when
  * reset_control_(de)assert has been used.
- * return 0.
  *
  * If rstc is NULL it is an optional reset and the function will just
  * return 0.
···
  * After calling this function, the reset is guaranteed to be deasserted.
  * Consumers must not use reset_control_reset on shared reset lines when
  * reset_control_(de)assert has been used.
- * return 0.
  *
  * If rstc is NULL it is an optional reset and the function will just
  * return 0.