psci: fix values of incorrectly defined constants

This patch fixes the following constant values in the psci.h:

1. The affinity level shift value in the power_state parameter of the
   cpu_suspend psci call. The previous value was preventing shutdown
   of the affinity level 1.

2. The values used for affinity state constants (ON, OFF,
   ON_PENDING). They did not match the values expected to be returned
   by the affinity_info psci api as mentioned in the spec.

3. The state id shift value in the power_state parameter of the
   cpu_suspend psci call.

Change-Id: I62ed5eb0e9640b4aa97b93923d6630e6b877a097
diff --git a/docs/change-log.md b/docs/change-log.md
index 3ae5fab..73d7e7a 100644
--- a/docs/change-log.md
+++ b/docs/change-log.md
@@ -49,6 +49,9 @@
     physically powered up to prevent a spurious wake up from a subsequent cpu
     off state.
 
+*   Definitions of some constants related to the PSCI api calls AFFINITY_INFO
+    and CPU_SUSPEND have been corrected.
+
 ARM Trusted Firmware - version 0.2
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