Only a very small handful of platforms support DEBUG_LL_UART_NONE but it
lurks in the menus of every single platform config ready to break the
build. This is an especial problem for defconfig/oldconfig since it is
often selected by default.

This patch solves the problem by removing this option. Any platforms
still depending upon this option must be migrated.
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>