OMAP: 4430SDP/Panda: rename HPD GPIO to CT_CP_HPD

The GPIO 60 on 4430sdp and Panda is not HPD GPIO, as currently marked in
the board files, but CT_CP_HPD, which is used to enable/disable HPD
functionality.

This patch renames the GPIO.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>