Increase the size of the vendor partition

With the addition of the 1.1 neural network HAL the pie vendor is
exactly full.

BUG: 28053261
Test: Local build
Change-Id: I62edcdbcc6ff1ec7d002ebf4ef4b72b8b3f45675
(cherry picked from commit 2eb904fb6abfc0f5ee2fcc5c71a6e1b05d08ee2f)
diff --git a/shared/BoardConfig.mk b/shared/BoardConfig.mk
index a2abb0d..322edf4 100644
--- a/shared/BoardConfig.mk
+++ b/shared/BoardConfig.mk
@@ -21,7 +21,7 @@
 # Build a separate vendor.img partition
 BOARD_USES_VENDORIMAGE := true
 BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE := ext4
-BOARD_VENDORIMAGE_PARTITION_SIZE := 100663296 # 96MB
+BOARD_VENDORIMAGE_PARTITION_SIZE := 268435456 # 256 MB
 TARGET_COPY_OUT_VENDOR := vendor
 
 TARGET_NO_RECOVERY := true