HDQ driver: Remove global pointer

This patch provides the necessary modifications to the driver to
remove the global ptr hdq_data.
Signed-off-by: Madhusudhan Chikkature <madhu.cr@ti.com>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Acked-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>