arm64: dts: uniphier: rename PH1-LD10 to PH1-LD20

Due to the company's awful projecting, this chip has been renamed to
PH1-LD20.  It has not been shipped yet, this change would have no
impact on our customers.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>