msm8953-common: Make a legacy symlink for persist as well

Apparently, our fingerprint hal wants it too.

Change-Id: I673646a90f016c3d0e3f2244bed8e31cd0263f7e

BoardConfigCommon.mk

@@ -184,7 +184,8 @@ BOARD_PERSISTIMAGE_PARTITION_SIZE := 33554432
 BOARD_FLASH_BLOCK_SIZE := 131072 # (BOARD_KERNEL_PAGESIZE * 64)
 BOARD_ROOT_EXTRA_SYMLINKS := \
     /vendor/dsp:/dsp \
-    /vendor/firmware_mnt:/firmware
+    /vendor/firmware_mnt:/firmware \
+    /mnt/vendor/persist:/persist
 TARGET_USES_MKE2FS := true
 
 # Peripheral manager