sony_acpi: Add acpi_bus_generate event

Added acpi_bus_generate event for forwarding Fn-keys pressed to acpi subsystem,
and made correspondent necessary changes for this to work.

Signed-off-by: Nilton Volpato <nilton.volpato@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Len Brown <len.brown@intel.com>