fastbootd: add read arg to OpenPartition

Allow it to read partitions.

Bug: 173654501
Test: pass

Change-Id: I115e84734dd258243ca3f4f1b373b06adcaa4080
diff --git a/fastboot/device/utility.h b/fastboot/device/utility.h
index 3b71ef0..c2646d7 100644
--- a/fastboot/device/utility.h
+++ b/fastboot/device/utility.h
@@ -75,7 +75,11 @@
 std::optional<std::string> FindPhysicalPartition(const std::string& name);
 bool LogicalPartitionExists(FastbootDevice* device, const std::string& name,
                             bool* is_zero_length = nullptr);
-bool OpenPartition(FastbootDevice* device, const std::string& name, PartitionHandle* handle);
+
+// If read, partition is readonly. Else it is write only.
+bool OpenPartition(FastbootDevice* device, const std::string& name, PartitionHandle* handle,
+                   bool read = false);
+
 bool GetSlotNumber(const std::string& slot, android::hardware::boot::V1_0::Slot* number);
 std::vector<std::string> ListPartitions(FastbootDevice* device);
 bool GetDeviceLockStatus();