omap: PM debug: fix wake-on-timer debugfs dependency

Wakeup-on-timer code does not have/need debugfs dependency.  Move
the function out of debugfs ifdef.

Fixes compile error when CONFIG_DEBUG_FS is disabled but PM debug is
enabled.

Reported-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>