ARM: mach-shmobile: ap4evb: Add ts_get_pendown_state for tsc2007

This function is necessary to ensure the detection of pen-down.
This patch support both QHD / WVGA pannel.

Tested-by: Tony SIM <chinyeow.sim.xt@renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>