[driver_host] Remove unused zx::channel from zx_device

This is never used, and the coordinator RPC connection lives in the
coordinator_rpc member.

Change-Id: I5100836eebd9891a04477ac8e4babdd547cd8d1a
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/442455
Commit-Queue: Simon Shields <simonshields@google.com>
Reviewed-by: Suraj Malhotra <surajmalhotra@google.com>
Testability-Review: Suraj Malhotra <surajmalhotra@google.com>
diff --git a/src/devices/bin/driver_host/zx_device.h b/src/devices/bin/driver_host/zx_device.h
index 6708598..71632b7 100644
--- a/src/devices/bin/driver_host/zx_device.h
+++ b/src/devices/bin/driver_host/zx_device.h
@@ -382,9 +382,6 @@
 
   char name_[ZX_DEVICE_NAME_MAX + 1] = {};
 
-  // The fuchsia.Device.Manager.Coordinator protocol
-  zx::channel coordinator_rpc_;
-
   friend class fbl::Recyclable<zx_device_t>;
   void fbl_recycle();