bp_activity_can_comment() not behaving the right way

[imath]

in r9698, the site option bp-disable-blogforum-comments was mistyped (extra 'd' in disable) causing the disable comments check to always be false.

[r-a-y]

Commit it! :)

[imath]

@r-a-y sure :) i've noticed this at work, couldn't commit it there!

[imath]

In 9751:

Make sure the correct site option is checked in bp_activity_can_comment()

The option to check is bp-disable-blogforum-comments. In r9698, the option was mistyped to bp-disabled-blogforum-comments.

Fixes #6374