[usb]: add more musb symbols

Signed-off-by: Imre Kaloz <kaloz@openwrt.org>


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39548 3c298f89-4303-0410-b956-a3cf2f4a3e73
[usb]: use musb in PIO mode, as DMA support is platform dependent

Signed-off-by: Imre Kaloz <kaloz@openwrt.org>


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39549 3c298f89-4303-0410-b956-a3cf2f4a3e73
[usb]: musb depends on usb-gadget support

Signed-off-by: Imre Kaloz <kaloz@openwrt.org>


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39550 3c298f89-4303-0410-b956-a3cf2f4a3e73