ARM: bcm2835: bcm2835_defconfig updates

Rebuild bcm2835_defconfig using "make bcm2835_defconfig;
make savedefconfig", and add the following features:

* Enable the DWC2 USB controller present in the BCM2835 SoC.
* Enable drivers for various USB-hosted devices, which make the
  controller useful.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>