Screen Add FDN: Disable Save button if fields Name or Number are empty

Disable the Save-button in the screen "Add fixed dialing number" if the
fields Name or Number fields are empty.

Bug: 70374738
Test: manual - checked that the save button is enabled and disabled
correctly.
Change-Id: Id99e8a42529e617e75298a07f16bd9666a19ad3b
2 files changed