Revert "Move architecture timer setup to platform-specific code"

This reverts commit 1c297bf015226c182b66498d5a64b8b51c7624f5
because it introduced a bug: the CNTFRQ_EL0 register was no
longer programmed by all CPUs.  bl31_platform_setup() function
is invoked only in the cold boot path and consequently only
on the primary cpu.

A subsequent commit will correctly implement the necessary changes
to the counter frequency setup code.

Fixes ARM-software/tf-issues#125

Conflicts:

	docs/firmware-design.md
	plat/fvp/bl31_plat_setup.c

Change-Id: Ib584ad7ed069707ac04cf86717f836136ad3ab54
diff --git a/docs/porting-guide.md b/docs/porting-guide.md
index 6bba360..56467fb 100644
--- a/docs/porting-guide.md
+++ b/docs/porting-guide.md
@@ -446,9 +446,8 @@
 for performing any remaining platform-specific setup that can occur after the
 MMU and data cache have been enabled.
 
-In the ARM FVP port, this function enables system-level implementation of the
-generic timer counter. It also initializes counter frequency for CPU's generic
-timers.
+In the ARM FVP port, it zeros out the ZI section and enables the system level
+implementation of the generic timer counter.
 
 This function is also responsible for initializing the storage abstraction layer
 which is used to load further bootloader images.
@@ -772,7 +771,6 @@
 The ARM FVP port does the following:
 *   Initializes the generic interrupt controller.
 *   Configures the CLCD controller.
-*   Initializes counter frequency for CPU's generic timer
 *   Grants access to the system counter timer module
 *   Initializes the FVP power controller device
 *   Detects the system topology.