Move xen_early_init() before efi_init(), then when calling efi_init()
could initialize Xen specific UEFI.
Check if it runs on Xen hypervisor through the flat dts.
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
Reviewed-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>