mtd: nand: denali_dt: enable HW_ECC_FIXUP for Altera SOCFPGA variant

There are various customizable parameters, so several variants for
this IP.  A generic compatible like "denali,denali-nand-dt" is
useless.  Moreover, there are multiple things wrong with this string.
(Refer to Rob's comment [1])

The "denali,denali-nand-dt" was added by Altera for the SOCFPGA port.
Replace it with a more specific string "altr,socfpga-denali-nand".
There are no users (in upstream) of the old compatible string.

The Denali IP on SOCFPGA incorporates the hardware ECC fixup engine.
So, this capability should be associated with the compatible.

[1] https://lkml.org/lkml/2016/12/1/450



Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>