ARM: dts: uniphier: update to new Denali NAND binding

ARM: dts: uniphier: update to new Denali NAND binding

With commit 911495cdfd85 ("mtd: rawnand: denali: decouple controller
and NAND chips"), the Denali NAND controller driver migrated to the
new controller/chip representation.

Update DT for it.

In the new binding, the number of connected chips are described in
DT instead of run-time probed.

I added just one chip to the reference boards, where we do not know
if the on-board NAND device is a single chip or multiple chips.
If we added too many chips into DT, it would end up with the timeout
error in nand_scan_ident().

I changed all the pinctrl properties to use the single CS.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>