ACPI: hotkey.c fixes, fix for potential crash of hotkey.c

While going through the code, I found out some memory leaks and potential
crashes in drivers/acpi/hotkey.c Please find the patch to fix them.

This patch does the following,

1. Fixes memory leaks in error paths of hotkey_write_config

2. Fixes freeing unallocated pointers in the error paths of hotkey_write_config

3. Uses a loop instead of linear searching for parsing the userspace
   input in get_params

4. Uses array of char * instead of passing 4 pointer parameters
   explicitly into the init_{poll_}hotkey_* static functions
Signed-off-by: Andrew Morton <akpm@osdl.org>
Acked-by: Luming Yu <luming.yu@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>