Tegra186: trampoline: update "System Suspend" exit criteria

The TZRAM memory loses its state during "System Suspend". This patch
check if TZRAM base address contains valid data, to decide if the system
is exiting from "System Suspend". To enable TZDRAM encryption, the Memory
Controller's TZDRAM base/size registers would be populated by the BPMP
when the system "wakes up".

Change-Id: I5fc8ba1ae3bce12f0ece493f6f9f5f4d92a46344
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

plat/nvidia/tegra/soc/t186/plat_trampoline.S

@@ -42,18 +42,14 @@
 /* CPU reset handler routine */
 func tegra186_cpu_reset_handler
 	/*
-	 * The Memory Controller loses state during System Suspend. We
-	 * use this information to decide if the reset handler is running
-	 * after a System Suspend. Resume from system suspend requires
-	 * restoring the entire state from TZDRAM to TZRAM.
+	 * The TZRAM loses state during System Suspend. We use this
+	 * information to decide if the reset handler is running after a
+	 * System Suspend. Resume from system suspend requires restoring
+	 * the entire state from TZDRAM to TZRAM.
 	 */
-	mov	x1, #TEGRA_MC_BASE
-	ldr	w0, [x1, #MC_SECURITY_CFG3_0]
-	lsl	x0, x0, #32
-	ldr	w0, [x1, #MC_SECURITY_CFG0_0]
-	adr	x1, tegra186_cpu_reset_handler
-	cmp	x0, x1
-	beq	boot_cpu
+	mov	x0, #BL31_BASE
+	ldr	x0, [x0]
+	cbnz	x0, boot_cpu
 
 	/* resume from system suspend */
 	mov	x0, #BL31_BASE