at91: Automatically detect USB feature
The sama7 sub target does not have USB support, the feature should not
be activated there. OpenWrt can automatically detect if the target
supports USB by using the scripts/target-metadata.pl script. With the
automatic detection USB support will only get activated on subtargest
which actually support USB like sam9x and sama5.
Signed-off-by: Hauke Mehrtens <[email protected]>
Hauke Mehrtens