HID: logitech-hidpp: Do not flood kernel log

Since commit 680ee411

 ("HID: logitech-hidpp: Fix connect event race")
the following messages appear in the kernel log from time to time:

logitech-hidpp-device 0003:046D:408A.0005: HID++ 4.5 device connected.
logitech-hidpp-device 0003:046D:408A.0005: HID++ 4.5 device connected.
logitech-hidpp-device 0003:046D:4051.0006: Disconnected
logitech-hidpp-device 0003:046D:408A.0005: Disconnected

As discussed, print the first per-device "device connected" message
at info level, demoting subsequent messages to debug level. Also,
demote the "Disconnected message" to debug level unconditionally.

Link: https://lore.kernel.org/lkml/3277085.44csPzL39Z@natalenko.name/
Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>