ir-rx51: Fix build after multiarch changes broke it

The ir-rx51 driver for n900 has been disabled since the multiarch
changes as plat include directory no longer is SoC specific.

Let's fix it with minimal changes to pass the dmtimer calls in
pdata. Then the following changes can be done while things can
be tested to be working for each change:

1. Change the non-pwm dmtimer to use just hrtimer if possible

2. Change the pwm dmtimer to use Linux PWM API with the new
   drivers/pwm/pwm-omap-dmtimer.c and remove the direct calls
   to dmtimer functions

3. Parse configuration from device tree and drop the pdata

Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: linux-media@vger.kernel.org
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Pali Rohár <pali.rohar@gmail.com>