[IA64] Rationalise Region Definitions

Currently, region numbers are defined in several files, with several 
names.  For example, we have REGION_KERNEL in asm/page.h and 
RGN_KERNEL in pgtable.h 
 
We also have address definitions that should depend on the 
RGN_XXX macros, but are currently just long constants. 
 
The following patch reorganises all the definitions so that they have 
the same form (RGN_XXX), are in one place, and that addresses that 
depend on RGN_XXX are derived from them. 

(This is a necessary but not sufficient patch to allow UML-like 
operation on IA64). 

Thanks to David Mosberger for catching the change I missed in mmu_context.h.
 
Signed-off-by: Peter Chubb <peterc@gelato.unsw.edu.au> 
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/asm-ia64/system.h b/include/asm-ia64/system.h
index cd2cf76..33256db 100644
--- a/include/asm-ia64/system.h
+++ b/include/asm-ia64/system.h
@@ -19,12 +19,13 @@
 #include <asm/pal.h>
 #include <asm/percpu.h>
 
-#define GATE_ADDR		__IA64_UL_CONST(0xa000000000000000)
+#define GATE_ADDR		RGN_BASE(RGN_GATE)
+
 /*
  * 0xa000000000000000+2*PERCPU_PAGE_SIZE
  * - 0xa000000000000000+3*PERCPU_PAGE_SIZE remain unmapped (guard page)
  */
-#define KERNEL_START		 __IA64_UL_CONST(0xa000000100000000)
+#define KERNEL_START		 (GATE_ADDR+0x100000000)
 #define PERCPU_ADDR		(-PERCPU_PAGE_SIZE)
 
 #ifndef __ASSEMBLY__