ARM: dts: socfpga: Fix NAND controller node compatible for Arria10

The NAND compatible "denali,denal-nand-dt" property has never been used and
is obsolete. Remove it.

Cc: stable@vger.kernel.org
Fixes: f549af06

("ARM: dts: socfpga: Add NAND device tree for Arria10")
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>