Skip decryption when installing mapped zips

Decrypting userdata is not needed when installing zips if we have
a map of blocks to read, so skip the decryption. This allows to
install zips with no user interaction and, more importantly, it
allows to install zips on devices where TWRP can't properly decrypt
userdata.

Remove also the unneeded Mount_All_Storage() call, Install_Command()
already mounts the needed partition.

Change-Id: I91c69f84ecc2fe41c9567c40649e501af1cfb64a

openrecoveryscript.cpp

@@ -141,7 +141,6 @@ int OpenRecoveryScript::run_script_file(void) {
 			if (strcmp(command, "install") == 0) {
 				// Install Zip
 				DataManager::SetValue("tw_action_text2", "Installing Zip");
-				PartitionManager.Mount_All_Storage();
 				ret_val = Install_Command(value);
 				install_cmd = -1;
 			} else if (strcmp(command, "wipe") == 0) {