ARM: dts: sunxi: remove duplicated entries in makefile

During introduction of DTS vendor subdirectories in 724ba675, sun8i
section of the makefile got duplicated. Clean that up.

Fixes: 724ba675 ("ARM: dts: Move .dts files to vendor sub-directories")
Signed-off-by: Pavel Löbl <pavel@loebl.cz>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Link: https://lore.kernel.org/r/20240320061027.4078852-1-pavel@loebl.cz


Signed-off-by: Chen-Yu Tsai <wens@csie.org>