factory reset: restore ext4 policy on /data/cache

If ext4 policy is not restored, system won't boot properly
after a factory reset.

When /data is formatted by the user, we need to make sure we
do not create the /data/cache directory so that Android can
create it with the new policy for /data.

This also removes extraneous umount calls, and places them
in the specific wipe function for each filesystem.

Change-Id: I71ff39d8660fbf4aa6fe8a8309e291166359da72
diff --git a/crypto/ext4crypt/e4policyget.cpp b/crypto/ext4crypt/e4policyget.cpp
old mode 100644
new mode 100755
index 05de86f..9211347
--- a/crypto/ext4crypt/e4policyget.cpp
+++ b/crypto/ext4crypt/e4policyget.cpp
@@ -23,13 +23,12 @@
 #define EXT4_KEY_DESCRIPTOR_SIZE_HEX 17
 
 int main(int argc, char *argv[]) {
-	bool ret = false;
 	if (argc != 2) {
 		printf("Must specify a path\n");
 		return -1;
 	} else  {
 		ext4_encryption_policy eep;
-		if (e4crypt_policy_get_struct(argv[1], &eep, sizeof(eep))) {
+		if (e4crypt_policy_get_struct(argv[1], &eep)) {
 			char policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
 			policy_to_hex(eep.master_key_descriptor, policy_hex);
 			printf("%s\n", policy_hex);