ARM: UniPhier: add UART initialization routine for low-level debug

The low-level debugging functions are useful to debug the early boot
stage where the full UART driver is not available.

UniPhier SoCs need to initialize the UART port 0 to use this feature.
The initialization routine is called at the very entry of the
lowlevel_init().

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/arch/arm/cpu/armv7/uniphier/ph1-ld4/Makefile b/arch/arm/cpu/armv7/uniphier/ph1-ld4/Makefile
index 8794629..0752906 100644
--- a/arch/arm/cpu/armv7/uniphier/ph1-ld4/Makefile
+++ b/arch/arm/cpu/armv7/uniphier/ph1-ld4/Makefile
@@ -5,6 +5,7 @@
 obj-$(CONFIG_DISPLAY_BOARDINFO) += board_info.o
 obj-$(if $(CONFIG_OF_CONTROL),,y) += platdevice.o
 obj-y += boot-mode.o
+obj-$(CONFIG_DEBUG_LL) += lowlevel_debug.o
 obj-$(CONFIG_SOC_INIT) += bcu_init.o sbc_init.o sg_init.o pll_init.o \
 								clkrst_init.o
 obj-$(CONFIG_BOARD_POSTCLK_INIT) += pinctrl.o