The HiSilicon Hi6220 USB PHY is available in HiSilicon Hi6220 SoCs only.
Restrict it to HiSilicon arm64, unless compile-testing.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NKishon Vijay Abraham I <kishon@ti.com>