This property was never needed, remove it. This also silences
dtbs_check warnings.

Fixes: b186b8b6 ("arm64: dts: freescale: add initial device tree for TQMa8Mx with i.MX8M")
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>