xilinx: versal: Add PSCI APIs for suspend/resume

Add following APIs in plat_psci to support suspend resume:
- versal_pwr_domain_off
- versal_pwr_domain_suspend
- versal_pwr_domain_suspend_finish
- versal_validate_power_state
- versal_get_sys_suspend_power_state

Signed-off-by: Tejas Patel <tejas.patel@xilinx.com>
Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Signed-off-by: Jolly Shah <jolly.shah@xilinx.com>
Change-Id: Ife908a45f32e2037c9c19e13211a8e4b373b8342
diff --git a/plat/xilinx/versal/include/plat_private.h b/plat/xilinx/versal/include/plat_private.h
index cb35be8..e302096 100644
--- a/plat/xilinx/versal/include/plat_private.h
+++ b/plat/xilinx/versal/include/plat_private.h
@@ -18,6 +18,8 @@
 void plat_versal_gic_cpuif_enable(void);
 void plat_versal_gic_cpuif_disable(void);
 void plat_versal_gic_pcpu_init(void);
+void plat_versal_gic_save(void);
+void plat_versal_gic_resume(void);
 
 unsigned int versal_calc_core_pos(u_register_t mpidr);