Distinguish usart and uart by read ip name register,
The usart read name is "USAR",
The uart and dbgu read name is "DBGU".

Signed-off-by: Elen Song <elen.song@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently early kernel messages, i.e., those from uncompression, go to the
debugging UART. And if it is enabled in the platform configuration, but
not initialized by the bootloader, the machine hangs, waiting for UART
status change. Besides, having those messages on another UART - typically
the console UART - may be preferrable. This patch allows selecting the
UART in kernel configuration.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Acked-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>