package/usbutils: bump to version 006

Also, as the kernel.org archives are back up, use them as official site
again.

[thomas.petazzoni@free-electrons.com: use BR2_KERNEL_MIRROR]

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>