Though the keyboard and other driver will continue to support the legacy
"gpio-key,wakeup", "nvidia,wakeup-source" boolean property to enable the
wakeup source, "wakeup-source" is the new standard binding.

This patch replaces all the legacy wakeup properties with the unified
"wakeup-source" property in order to avoid any further copy-paste
duplication.

Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: linux-tegra@vger.kernel.org
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>