usb: Add environment based device ignorelist

usb: Add environment based device ignorelist

Add the environment variable "usb_ignorelist" to prevent USB devices
listed in it from being bound to drivers. This allows to ignore devices
which are undesirable or trigger bugs in u-boot's USB stack.
Devices emulating keyboards are one example of undesirable devices as
u-boot currently supports only a single USB keyboard device. Most
commonly, people run into this with Yubikeys, so let's ignore those in
the default environment.

Based on previous USB keyboard specific patches for the same purpose.

Link: https://lore.kernel.org/u-boot/7ab604fb-0fec-4f5e-8708-7a3a7e2cb568@denx.de/
Reviewed-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Janne Grunau <j@jannau.net>