ARM: bcm2835: enable USB_DWC2_HOST in defconfig

It broke when host was moved into a separate module, in 47a1685f

 ("usb:
dwc2/s3c-hsotg: move s3c-hsotg into dwc2 directory"),

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>