[OpenCL] Fixes device path to name with many colons

[jwlawson]

The device path is constructed from a device name by replacing all colons with underscores. Some device names contain more than one colon, for example device:SYCL:0 which gives a path device_SYCL_0. The previous code would not convert this back to the original device name, but rather to device:SYCL_0.

An alternative fix would be to convert all underscores to colons in the device name (i.e. remove the restriction inside replace("_", ":", 1) to just replace("_", ":")), however this would cause problems if there are any device names which are meant to contain underscores.

I'm not too sure what would be the best way of doing this.

[jwlawson]

This fixes test fails:

//tensorflow/python/debug:dumping_wrapper_test
//tensorflow/python/debug:local_cli_wrapper_test
//tensorflow/python/debug:source_utils_test

And partially fixes:

//tensorflow/python/debug:session_debug_file_test
//tensorflow/python/debug:analyzer_cli_test