usb: host: Enable compile testing for some of drivers

Some of the USB host drivers can be compile tested to increase build
coverage.  Add 'if' conditional to 'default y' so they will not get
enabled by default on all other architectures.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20191230172215.17370-1-krzk@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>