sandbox: Correct SDL build flags

The check for CONFIG_SANDBOX_SDL in config.mk does not work since the
build config is not available by the time that file is included. Remove it
so that we always call sdl-config except when NO_SDL is used.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/config.mk b/arch/sandbox/config.mk
index 7226b7b..31a12db 100644
--- a/arch/sandbox/config.mk
+++ b/arch/sandbox/config.mk
@@ -11,11 +11,9 @@
 ifneq ($(NO_SDL),)
 PLATFORM_CPPFLAGS += -DSANDBOX_NO_SDL
 else
-ifdef CONFIG_SANDBOX_SDL
 PLATFORM_LIBS += $(shell sdl-config --libs)
 PLATFORM_CPPFLAGS += $(shell sdl-config --cflags)
 endif
-endif
 
 cmd_u-boot__ = $(CC) -o $@ -Wl,-T u-boot.lds $(u-boot-init) \
 	-Wl,--start-group $(u-boot-main) -Wl,--end-group \
diff --git a/arch/sandbox/cpu/sdl.c b/arch/sandbox/cpu/sdl.c
index f668f53..080c7c8 100644
--- a/arch/sandbox/cpu/sdl.c
+++ b/arch/sandbox/cpu/sdl.c
@@ -6,7 +6,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include <linux/input.h>
-#include <SDL/SDL.h>
+#include <SDL.h>
 #include <asm/state.h>
 
 /**