Set file system types for mainline_arm64 partitions

This config was in a weird state where it sets the OUT
directory for these partitions but not the file system
type. Within the build system, both of these variables
are used interchangeably to check whether these partitions
are expected to be present.

A typical mainline device is expected to /vendor and
/product, so just add these.

Bug: 120974093
Test: make
Change-Id: I803d7afdcadc37e4384ae80f08bc1c8db535d2f4
diff --git a/target/board/BoardConfigGsiCommon.mk b/target/board/BoardConfigGsiCommon.mk
index 68d29c8..a0f43af 100644
--- a/target/board/BoardConfigGsiCommon.mk
+++ b/target/board/BoardConfigGsiCommon.mk
@@ -27,6 +27,7 @@
 
 # GSI forces product packages to /system for now.
 TARGET_COPY_OUT_PRODUCT := system/product
+BOARD_PRODUCTIMAGE_FILE_SYSTEM_TYPE :=
 
 # Creates metadata partition mount point under root for
 # the devices with metadata parition
diff --git a/target/board/BoardConfigMainlineCommon.mk b/target/board/BoardConfigMainlineCommon.mk
index e13317f..5f2d300 100644
--- a/target/board/BoardConfigMainlineCommon.mk
+++ b/target/board/BoardConfigMainlineCommon.mk
@@ -10,7 +10,10 @@
 
 # Mainline devices must have /vendor and /product partitions.
 TARGET_COPY_OUT_VENDOR := vendor
+BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE := ext4
+
 TARGET_COPY_OUT_PRODUCT := product
+BOARD_PRODUCTIMAGE_FILE_SYSTEM_TYPE := ext4
 
 # system-as-root is mandatory from Android P
 TARGET_NO_RECOVERY := true