phc2sys: update open_clock and deprecate '-i' option

This patch modifies phc2sys to enable the use of interface names in clock_open
rather than having to do that by hand. This enables cleaner use of the -s and -c
options as they can accept interface names. This also enables the user to set
the slave clock by network interface as well.

-v2-
* fix clock_open as it used device instead of phc_device in the final call to phc_open

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
phc2sys: update usage/error reporting

This patch updates phc2sys usage reporting to give a slightly better indication
of why the program was unable to run.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>