ARC: [plat-arcfpga] DT arc-uart bindings change: "baud" => "current-speed"

Per Grant's review comment - driver changes via tty tree

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: Ensure CONFIG_VIRT_TO_BUS is not enabled

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Reported-by: James Hogan <james.hogan@imgtec.com>