hsi: Build hsi_boardinfo.c into hsi core if enabled

If the HSI core is built as a module hsi_boardinfo may still
be built-in as its Kconfig type is bool, which can cause build
issues. Fix this by building this code into the HSI core when
enabled.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
diff --git a/drivers/hsi/Makefile b/drivers/hsi/Makefile
index 360371e..9694478 100644
--- a/drivers/hsi/Makefile
+++ b/drivers/hsi/Makefile
@@ -1,7 +1,8 @@
 #
 # Makefile for HSI
 #
-obj-$(CONFIG_HSI_BOARDINFO)	+= hsi_boardinfo.o
 obj-$(CONFIG_HSI)		+= hsi.o
+hsi-objs			:= hsi_core.o
+hsi-$(CONFIG_HSI_BOARDINFO)	+= hsi_boardinfo.o
 obj-y				+= controllers/
 obj-y				+= clients/