arm: sunxi: do not force USB for arch-sunxi

arm: sunxi: do not force USB for arch-sunxi

Currently, USB is forced-enabled for the sunxi familly, and there is no
way to disable it.

However, USB takes a long time to initiliase, delaying the boot by up to
5 seconds (without any USB device attached!). This is a very long delay,
especially in cases where USB booting is not wanted at all, and where
the device is expected to boot relatively often (even in production).

Change the way the dependencies are handled, by only forcibly selecting
USB when CONFIG_DISTRO_DEFAULTS ("defaults suitable for booting general
purpose Linux distributions") is set. This option defaults to y for the
sunxi familly, so the current default behaviour is kept unchanged. Users
interested in boot time and/or size will be able to disable this to
further disable USB.

With USB disabled, the time spent in U-Boot before handing control to
the Linux kernel is about 1s now, down from ~5s (Nanopi Neo, sunxi H3).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Ian Campbell <ijc@hellion.org.uk>
Cc: Hans De Goede <hdegoede@redhat.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>