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

Replace some bare constants with power states.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c
index 4147267..1dd1a38 100644
--- a/arch/arm/mach-omap2/powerdomain.c
+++ b/arch/arm/mach-omap2/powerdomain.c
@@ -158,7 +158,7 @@
 {
 	int i;
 
-	for (i = 0; i < 4; i++)
+	for (i = 0; i < PWRDM_MAX_PWRSTS; i++)
 		pwrdm->state_counter[i] = 0;
 
 	pwrdm_wait_transition(pwrdm);