Since the GXL family has S905X and S905D SoCs, we're keeping the SoC
name in the DTS filename for clarity.  Rename this file accordingly to
be consistent with the rest of the GXL DTS files.

Cc: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>