pwm: Updated API

* Greater use of maa_result_t
* Added raw mode.
* Updated cycle-pwm3 to use new api.

Signed-off-by: Thomas Ingleby <thomas.c.ingleby@intel.com>

examples/cycle-pwm3.c

@@ -30,7 +30,7 @@ int
 main ()
 {
     maa_pwm_context* pwm;
-    pwm = maa_pwm_init(0, 3);
+    pwm = maa_pwm_init(3);
     if (pwm == NULL) {
         return 1;
     }