This patch removes the unnecessary UART4 platform which is under
data is wrong because of this

There is a separate platform structure for UART4
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-By: NKevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>