kbuild: Remove uncmd_spl logic

At this point in the conversion there should be no need to have logic to
disable some symbol during the SPL build as all symbols should have an
SPL counterpart.

The main real changes done here are that we now must make proper use of
CONFIG_IS_ENABLED(DM_SERIAL) rather than many of the odd tricks we
developed prior to CONFIG_IS_ENABLED() being available.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 33fa568..37d3f82 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -3,30 +3,15 @@
 # (C) Copyright 2006-2009
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 
-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
+ifeq ($(CONFIG_$(SPL_TPL_)DM_SERIAL),y)
 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_PL011_SERIAL) += serial_pl01x.o
 obj-$(CONFIG_$(SPL_)SYS_NS16550_SERIAL) += serial_ns16550.o
-endif
 
 obj-$(CONFIG_ALTERA_UART) += altera_uart.o
 obj-$(CONFIG_ALTERA_JTAG_UART) += altera_jtag_uart.o