Account for multiple BOARD_PLAT_PUBLIC[PRIVATE]_SEPOLICY_DIR dirs

After https://android-review.googlesource.com/688488
BOARD_PLAT_PUBLIC[PRIVATE]_SEPOLICY_DIR can now specify multiple
directories.

Bug: n/a
Test: build sepolicy

Change-Id: Id850327c29bc626d3d721935edcb2b7afd2fd283
diff --git a/core/soong_config.mk b/core/soong_config.mk
index ea3714a..3f1fb66 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -143,8 +143,8 @@
 
 $(call add_json_list, BoardVendorSepolicyDirs,           $(BOARD_SEPOLICY_DIRS))
 $(call add_json_list, BoardOdmSepolicyDirs,              $(BOARD_ODM_SEPOLICY_DIRS))
-$(call add_json_str,  BoardPlatPublicSepolicyDir,        $(BOARD_PLAT_PUBLIC_SEPOLICY_DIR))
-$(call add_json_str,  BoardPlatPrivateSepolicyDir,       $(BOARD_PLAT_PRIVATE_SEPOLICY_DIR))
+$(call add_json_list, BoardPlatPublicSepolicyDirs,       $(BOARD_PLAT_PUBLIC_SEPOLICY_DIR))
+$(call add_json_list, BoardPlatPrivateSepolicyDirs,      $(BOARD_PLAT_PRIVATE_SEPOLICY_DIR))
 
 _contents := $(_contents)    "VendorVars": {$(newline)
 $(foreach namespace,$(SOONG_CONFIG_NAMESPACES),\