accept proper number style condition != as not equal operator, fdo#76777

ODF 1.2 specifies '!=' as not equal operator in <number:number-style>
<style:map> style:condition attribute. So far '<>' is written, accept
the correct operator.

Change-Id: I6087992ee35fff5c7aa52b7cec2b83b0a78dbac1
(cherry picked from commit dfcc851d65c8d81988843ef31a75b5d30051ddfd)
Reviewed-on: https://gerrit.libreoffice.org/8836
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>