devel/sope2: remove BROKEN_aarch64 after 8690517a

The port works now, but previous committer forgot to
remove BROKEN_aarch64.

Fixes: 8690517ab0871935aae7f95a305c9b8815993b14
Approved by: portmgr (build fix blanket)
Approved by: eduardo (mentor)
Differential Revision: https://reviews.freebsd.org/D38679