Resolve "Reicast: add VMUs to every connected pad"

Please make sure your MR is ready to be merged !

• You added the changes in CHANGELOG.md
• You described the MR as below
• You updated the recalbox wiki
• You wrote a blog post on recalbox-blog

Changes :

• each pad now has his 2 VMU, which makes it up to 8 possible VMUs

Related to :

• link other PR or issues here

Closes #234 (closed)