Reduce deep nesting of header files

Reduce the number of header files included from other header
files as much as possible without splitting the files. Use forward
declarations where possible. This allows removal of some unnecessary
"#ifndef __ASSEMBLY__" statements.

Also, review the .c and .S files for which header files really need
including and reorder the #include statements alphabetically.

Fixes ARM-software/tf-issues#31

Change-Id: Iec92fb976334c77453e010b60bcf56f3be72bd3e
diff --git a/include/bl31/services/psci.h b/include/bl31/services/psci.h
index ab7b7bd..570fe5b 100644
--- a/include/bl31/services/psci.h
+++ b/include/bl31/services/psci.h
@@ -31,6 +31,7 @@
 #ifndef __PSCI_H__
 #define __PSCI_H__
 
+
 /*******************************************************************************
  * Defines for runtime services func ids
  ******************************************************************************/
@@ -131,6 +132,10 @@
 #define PSCI_NUM_AFFS		32ull
 
 #ifndef __ASSEMBLY__
+
+#include <stdint.h>
+
+
 /*******************************************************************************
  * Structure populated by platform specific code to export routines which
  * perform common low level pm functions