ARM: dts: omap4-droid4: fix dts w.r.t. pwm

pwm node should not be under gpio6 node in the device tree.

This fixes detection of the pwm on Droid 4.

Fixes: 6d7bdd32

 ("ARM: dts: omap4-droid4: update touchscreen")
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
[tony@atomide.com: added fixes tag]
Signed-off-by: Tony Lindgren <tony@atomide.com>