serial: Fix Makefile during SPL and TPL build

This patch fixes a situation where CONFIG_DM_SERIAL is enabled for
regular U-Boot and SPL, but not for TPL. In that case, the build
will try to include serial-uclass into the TPL nonetheless, because
CONFIG_DM_SERIAL is set.

The solution is to check if the build is for SPL or TPL and in that
case, check if CONFIG_$(SPL_TPL_)DM_SERIAL is also set. Only in that
case, include serial-uclass.c . If the build is for regular U-Boot,
CONFIG_BUILD is not set, so only check if CONFIG_DM_SERIAL is set
and if so, include serial-uclass.c
Signed-off-by: NMarek Vasut <marek.vasut+renesas@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>

drivers/serial/Makefile

@@ -5,11 +5,27 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
+ifdef CONFIG_SPL_BUILD
+
+ifeq ($(CONFIG_$(SPL_TPL_)BUILD)$(CONFIG_$(SPL_TPL_)DM_SERIAL),yy)
+obj-y += serial-uclass.o
+else
+obj-y += serial.o
+endif
+
+else
+
 ifdef CONFIG_DM_SERIAL
-obj-$(CONFIG_$(SPL_TPL_)DM_SERIAL) += serial-uclass.o
-obj-$(CONFIG_PL01X_SERIAL) += serial_pl01x.o
+obj-y += serial-uclass.o
 else
 obj-y += serial.o
+endif
+
+endif
+
+ifdef CONFIG_DM_SERIAL
+obj-$(CONFIG_PL01X_SERIAL) += serial_pl01x.o
+else
 obj-$(CONFIG_PL010_SERIAL) += serial_pl01x.o
 obj-$(CONFIG_PL011_SERIAL) += serial_pl01x.o
 obj-$(CONFIG_SYS_NS16550_SERIAL) += serial_ns16550.o