cuttlefish: properly set reserve_root.

It's part of the mount options.

Bug: 146419093
Test: getprop | grep -i vold.has_reserved shows [1]
Change-Id: I99a7b3db35788f2f14913454b7318e441ddbf505
diff --git a/shared/config/fstab b/shared/config/fstab
index d81a527..73e5112 100644
--- a/shared/config/fstab
+++ b/shared/config/fstab
@@ -1,7 +1,7 @@
 boot /boot emmc defaults recoveryonly
 system /system ext4 noatime,ro,errors=panic wait,logical,first_stage_mount,slotselect
 # Add all non-dynamic partitions except system, after this comment
-/dev/block/by-name/userdata /data f2fs nodev,noatime,nosuid,inlinecrypt latemount,wait,fileencryption=aes-256-xts:aes-256-cts:v2+inlinecrypt_optimized,fsverity,keydirectory=/metadata/vold/metadata_encryption,reserve_root=32768
+/dev/block/by-name/userdata /data f2fs nodev,noatime,nosuid,inlinecrypt,reserve_root=32768 latemount,wait,fileencryption=aes-256-xts:aes-256-cts:v2+inlinecrypt_optimized,fsverity,keydirectory=/metadata/vold/metadata_encryption
 /dev/block/by-name/cache /cache ext4 nodev,noatime,nosuid,errors=panic wait
 /dev/block/by-name/metadata /metadata ext4 nodev,noatime,nosuid,errors=panic wait,formattable,first_stage_mount
 /dev/block/by-name/misc /misc emmc defaults defaults