maemo/gtk+2.0-maemo: remove version from provides
With this patch and pmbootstrap!1851 (merged), finally resolve the long-standing issue that gtk+2.0-maemo would get installed by pmbootstrap whenever something depends on gtk+2.0. (Currently on x86_64 only, because maemo is disabled for other arches, but still very annoying.)
I've verified that doing 'pmbootstrap install' with qemu-amd64 and hildon as selected UI still results in gtk+2.0-maemo getting installed.