console: Avoid positive return code from unregister_console()

There are only two callers that use the returned code from
unregister_console():

  - unregister_early_console() in arch/m68k/kernel/early_printk.c
  - kgdb_unregister_nmi_console() in drivers/tty/serial/kgdb_nmi.c

They both expect to get "0" on success and a non-zero value on error.
But the current behavior is confusing and buggy:

  - _braille_unregister_console() returns "1" on success
  - unregister_console() returns "1" on error

Fix and clean up the behavior:

  - Return success when _braille_unregister_console() succeeded
  - Return a meaningful error code when the console was
    not registered before

Link: http://lkml.kernel.org/r/[email protected]
To: [email protected]
To: Steven Rostedt <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>

0 files changed, 0 insertions, 0 deletions