emulators/qemu-sbruno: bump PORTREVISION for recent DEPRECATION

DEPRECATED was added in r533075 and gets encoded in the pkg; make sure that
users of the pkg get the notice far in advance that this port is going away,
as it will not receive any further updates that would trigger the rebuild.

Approved by: koobs (mentor)
MFH: 2020Q2 (blanket: metadata correction)