fdts: Fix stdout-path in various platforms

The value of stdout-path is a string and as a result, we can't use a
label as a reference to the serial0 node. This change fixes the
stdout-path property for N1SDP, Morello and TC0 by pointing to the
right alias.

Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Change-Id: I3d403389a424569be56327fab4140fec06f96d37
3 files changed