usb: typos 'requird', 'current'

%s/requird/required/
%s/current XHCI/currently XHCI/

Reviewed-by: Marek Vasut <marek.vasut@mailbox.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>