feat(rockchip): add RK3566/RK3568 Socs support

RK3566/RK3568 is a Quad-core soc and Cortex-a55 inside.
This patch supports the following functions:
1. basic platform setup
2. power up/off cpus
3. suspend/resume cpus
4. suspend/resume system
5. reset system

Signed-off-by: shengfei Xu <xsf@rock-chips.com>
Change-Id: I8b98a4d07664de26bd6078f63664cbc3d9c1c68c
diff --git a/lib/cpus/aarch64/dsu_helpers.S b/lib/cpus/aarch64/dsu_helpers.S
index 8e5b459..3c5bf2e 100644
--- a/lib/cpus/aarch64/dsu_helpers.S
+++ b/lib/cpus/aarch64/dsu_helpers.S
@@ -24,6 +24,7 @@
 	 */
 	.globl	check_errata_dsu_798953
 	.globl	errata_dsu_798953_wa
+	.globl	dsu_pwr_dwn
 
 func check_errata_dsu_798953
 	mov	x2, #ERRATA_APPLIES
@@ -202,3 +203,15 @@
 1:
 	ret	x8
 endfunc errata_dsu_2313941_wa
+
+	/* ---------------------------------------------
+	 * controls power features of the cluster
+	 * 1. Cache portion power not request
+	 * 2. Disable the retention circuit
+	 * ---------------------------------------------
+	 */
+func dsu_pwr_dwn
+	msr	CLUSTERPWRCTLR_EL1, xzr
+	isb
+	ret
+endfunc dsu_pwr_dwn