Introduce arm_setup_page_tables() function

This patch introduces the arm_setup_page_tables() function to
set up page tables on ARM platforms. It replaces the
arm_configure_mmu_elx() functions and does the same thing except
that it doesn't enable the MMU at the end. The idea is to reduce
the amount of per-EL code that is generated by the C preprocessor
by splitting the memory regions definitions and page tables creation
(which is generic) from the MMU enablement (which is the only per-EL
configuration).

As a consequence, the call to the enable_mmu_elx() function has been
moved up into the plat_arch_setup() hook. Any other ARM standard
platforms that use the functions `arm_configure_mmu_elx()` must be
updated.

Change-Id: I6f12a20ce4e5187b3849a8574aac841a136de83d
diff --git a/plat/xilinx/zynqmp/bl31_zynqmp_setup.c b/plat/xilinx/zynqmp/bl31_zynqmp_setup.c
index 6f1a18b..2ea8b1c 100644
--- a/plat/xilinx/zynqmp/bl31_zynqmp_setup.c
+++ b/plat/xilinx/zynqmp/bl31_zynqmp_setup.c
@@ -147,18 +147,18 @@
 }
 
 /*
- * Perform the very early platform specific architectural setup here. At the
- * moment this is only intializes the MMU in a quick and dirty way.
+ * Perform the very early platform specific architectural setup here.
  */
 void bl31_plat_arch_setup(void)
 {
 	plat_arm_interconnect_init();
 	plat_arm_interconnect_enter_coherency();
 
-	arm_configure_mmu_el3(BL31_RO_BASE,
+	arm_setup_page_tables(BL31_RO_BASE,
 			      BL31_COHERENT_RAM_LIMIT - BL31_RO_BASE,
 			      BL31_RO_BASE,
 			      BL31_RO_LIMIT,
 			      BL31_COHERENT_RAM_BASE,
 			      BL31_COHERENT_RAM_LIMIT);
+	enable_mmu_el3(0);
 }