firmware: dmi: Optimize dmi_matches

firmware: dmi: Optimize dmi_matches

Function dmi_matches can me made a bit faster:

* The documented purpose of dmi_initialized is to catch too early
  calls to dmi_check_system(). I'm not fully convinced it justifies
  slowing down the initialization of all systems out there, but at
  least the check should not have been moved from dmi_check_system()
  to dmi_matches(). dmi_matches() is being called for every entry of
  the table passed to dmi_check_system(), causing the same redundant
  check to be performed again and again. So move it back to
  dmi_check_system(), reverting this specific portion of commit
  d7b1956fed33 ("DMI: Introduce dmi_first_match to make the interface
  more flexible").

* Don't check for the exact_match flag again when we already know its
  value.

Signed-off-by: Jean Delvare <[email protected]>
Fixes: d7b1956fed33 ("DMI: Introduce dmi_first_match to make the interface more flexible")
Cc: Jani Nikula <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Jeff Garzik <[email protected]>