Remove an unneeded check in LocalPrinterHandlerChromeos::StartPrint()

In StartPrint(), the settings will always have a kSettingDeviceName key.
Stop checking if it does and filling in an empty device name in case it
is missing.

Change-Id: I797d4464c6ab954f634f85e08bb961ce0baaa6ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4549721


Commit-Queue: Lei Zhang <thestig@chromium.org>
Code-Coverage: Findit <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Benjamin Gordon <bmgordon@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1146684}