OMAP4: PM: remove redundant #ifdef CONFIG_PM

pm44xx.c is built only when CONFIG_PM is setup,
remove redundant CONFIG_PM check.

This also fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=25022



Reported-by: Martin Etti <ettl.martin@gmx.de>

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>