tests/Makefile.inc: Add missing KCONFIG_SPITCONFIG trailing slash

New version of kconfig requires trailing slash at the end of
KCONFIG_SPLITCONFIG to indicate that it is a directory path.

Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Change-Id: I1a11eca21c4aa5a6260006c4ba2cb419eca8a802
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56337
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/tests/Makefile.inc b/tests/Makefile.inc
index 2ae20a2..b4b8cda 100644
--- a/tests/Makefile.inc
+++ b/tests/Makefile.inc
@@ -24,7 +24,7 @@
 TEST_KCONFIG_AUTOHEADER := $(testobj)/config.src.h
 TEST_KCONFIG_AUTOCONFIG := $(testobj)/auto.conf
 TEST_KCONFIG_DEPENDENCIES := $(testobj)/auto.conf.cmd
-TEST_KCONFIG_SPLITCONFIG := $(testobj)/config
+TEST_KCONFIG_SPLITCONFIG := $(testobj)/config/
 TEST_KCONFIG_TRISTATE := $(testobj)/tristate.conf
 
 TEST_CFLAGS = -include $(src)/include/kconfig.h \