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.