ARM: uniphier: rework UniPhier SoC select in Kconfig

The chains of "depends on <SoC_name>" in the current Kconfig is
clumsy.  The idea here is to allow users to choose a SoC group first
(SoC group consists of some SoCs that can coexist in one binary).
Then, allow to enable/disable each SoC support in the selected SoC
group.  This makes the Kconfig menu clearer.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/configs/uniphier_ld4_sld8_defconfig b/configs/uniphier_ld4_sld8_defconfig
index 892bccc..4d7afb8 100644
--- a/configs/uniphier_ld4_sld8_defconfig
+++ b/configs/uniphier_ld4_sld8_defconfig
@@ -1,8 +1,7 @@
 CONFIG_ARM=y
 CONFIG_ARCH_UNIPHIER=y
 CONFIG_SYS_MALLOC_F_LEN=0x2000
-CONFIG_ARCH_UNIPHIER_PH1_LD4=y
-CONFIG_ARCH_UNIPHIER_PH1_SLD8=y
+CONFIG_ARCH_UNIPHIER_LD4_SLD8=y
 CONFIG_MICRO_SUPPORT_CARD=y
 CONFIG_SYS_TEXT_BASE=0x84000000
 CONFIG_DEFAULT_DEVICE_TREE="uniphier-ph1-ld4-ref"