Staging: lustre: Fix return in void function warning

This fixes checkpatch.pl warning:

WARNING: void function return statements are not generally useful
Signed-off-by: NDarshana Padmadas <darshanapadmadas@gmail.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/include/linux/libcfs/libcfs_prim.h

@@ -83,6 +83,5 @@ static inline void cfs_memory_pressure_restore(int old)
 		memory_pressure_set();
 	else
 		memory_pressure_clr();
-	return;
 }
 #endif