arm64: zynqmp: Enable EFI secure boot

Enabling EFI secure boot which is required for EBBR specification.
Enabling this will fix
"RT.SetVariable - Create one Time Base Auth Variable, the expect return
status should be EFI_SUCCESS"

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

configs/xilinx_zynqmp_virt_defconfig

@@ -189,3 +189,4 @@ CONFIG_EFI_RUNTIME_UPDATE_CAPSULE=y
 CONFIG_EFI_CAPSULE_ON_DISK=y
 CONFIG_EFI_CAPSULE_FIRMWARE_FIT=y
 CONFIG_EFI_CAPSULE_FIRMWARE_RAW=y
+CONFIG_EFI_SECURE_BOOT=y