Prefix device log messages with the device's sysname so it's more obvious
where the messages are coming from. This makes it much easier to grep for a
specific device's messages but also adds some identifier to messages that
were previously without any identifier (e.g. all the state machine debugging)

All info and error messages also automatically prefix the device name, so
those messages are standardised too, e.g

an info message now:
  event4  - SynPS/2 Synaptics TouchPad: is tagged by udev as: Touchpad
a debug message now:
  event4  - using pressure-based touch detection

And since this required changing a lot of the strings in messages anyway,
polish a few minor things too.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Acked-by: Hans de Goede <hdegoede@redhat.com>