ARM: dts: Unify pwm-omap-dmtimer node names

[ Upstream commit 4f15fc7c ]

There is no reg property for pwm-omap-dmtimer.

Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Stable-dep-of: ac08bda1 ("ARM: dts: ti: omap: motorola-mapphone: Fix abe_clkctrl warning on boot")
Signed-off-by: Sasha Levin <sashal@kernel.org>