samsung/exynos*/Makefile.inc: Simplify unnecessary ifeq

It's not needed, as we can use a simpler macro instead.

Change-Id: Ib96f5cfa434d0383ee3bfe49995a8f8830987f20
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/7925
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Tested-by: build bot (Jenkins)

src/soc/samsung/exynos5250/Makefile.inc

@@ -21,9 +21,7 @@ romstage-y += dmc_init_ddr3.c
 romstage-y += power.c
 romstage-y += mct.c
 romstage-y += monotonic_timer.c
-ifeq ($(CONFIG_DRIVERS_UART),y)
-romstage-y += uart.c
-endif
+romstage-$(CONFIG_DRIVERS_UART) += uart.c
 romstage-y += wakeup.c
 romstage-y += gpio.c
 romstage-y += timer.c

src/soc/samsung/exynos5420/Makefile.inc

@@ -22,9 +22,7 @@ romstage-y += dmc_init_ddr3.c
 romstage-y += power.c
 romstage-y += mct.c
 romstage-y += monotonic_timer.c
-ifeq ($(CONFIG_DRIVERS_UART),y)
-romstage-y += uart.c
-endif
+romstage-$(CONFIG_DRIVERS_UART) += uart.c
 romstage-y += wakeup.c
 romstage-y += gpio.c
 romstage-y += timer.c