OMAP powerdomain/PM: use symbolic constants for the max number of power states

Replace some bare constants with symbolic constants.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-omap2/powerdomain.c

@@ -122,7 +122,7 @@ static int _pwrdm_register(struct powerdomain *pwrdm)
 	list_add(&pwrdm->node, &pwrdm_list);
 
 	/* Initialize the powerdomain's state counter */
-	for (i = 0; i < 4; i++)
+	for (i = 0; i < PWRDM_MAX_PWRSTS; i++)
 		pwrdm->state_counter[i] = 0;
 
 	pwrdm_wait_transition(pwrdm);