xkb: fix XkbSetMap check for the keytypes count

The previous if/else condition resulted in us always setting the key
type count to the current number of key types. Split this up correctly.

Regression introduced in de940e06

Fixes #1249

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
4 jobs for wip/xkb-types-fix in 3 minutes and 11 seconds (queued for 19 seconds)