cpufreq: OMAP: remove unused <plat/omap-pm.h>

The <plat/*.h> headers are going away, and this one is not used.  remove it.
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Kevin Hilman <khilman@ti.com>

drivers/cpufreq/omap-cpufreq.c

@@ -31,7 +31,6 @@
 #include <asm/cpu.h>
 
 #include <plat/clock.h>
-#include <plat/omap-pm.h>
 #include <plat/common.h>
 #include <plat/omap_device.h>