Introduce vcpu_reset and refactor arch_cpu_init

Introduce vcpu_reset calling arch_cpu_init and arch_regs_reset.
vcpu_reset is called from main on cold boot or resume from CPU off.
arch_cpu_init gets a cpu and entry point parameter passed to
PSCI resume function.

Change-Id: I809b453c32b418237b7334d13d8e55916d593b09
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/src/arch/fake/hypervisor/cpu.c b/src/arch/fake/hypervisor/cpu.c
index 78b46f2..e00f71f 100644
--- a/src/arch/fake/hypervisor/cpu.c
+++ b/src/arch/fake/hypervisor/cpu.c
@@ -44,3 +44,9 @@
 	r->arg[6] = v.arg6;
 	r->arg[7] = v.arg7;
 }
+
+void arch_cpu_init(struct cpu *c, ipaddr_t entry_point)
+{
+	(void)c;
+	(void)entry_point;
+}