arm: mvebu: add another earlyprintk Kconfig option

In order to support both old and new bootloaders, we add a new Kconfig
option for the earlyprintk UART selection. The existing option allows
to work with old bootloaders (that keep the internal registers mapped
at 0xd0000000), while the newly introduced option allows to work with
new bootloaders (that remap the internal registers at 0xf1000000).

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>