ARM: uniphier: update UMC_MEMMAPSET value for LD20 SoC

Change bnk_typ's value from 8 to 0 (for G1's performance).

Signed-off-by: Wataru Okoshi <okoshi.wataru@socionext.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>