Input: pcspkr - fix code style and error value in pcspkr_event

This patch fixes the following issues in pcspkr:

* Return -EINVAL when input arguments are not valid in pcspkr_event
  function instead of -1.
* Replace <asm/io.h> with <linux/io.h>
* Fix indentation of case blocks in switch statement
* Reduce length of line 28 to less than 80 characters

The style issues were discovered by checkpatch.pl script.

Signed-off-by: Munir Contractor <munircontractor@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>