Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/c563e12f6af9
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Merge pull request #16020 from dominickuo/revert-bug-946556

Revert "Bug 946556 - [Music] Disable the play controls when using a bluetooth headset in a call

========

https://hg.mozilla.org/integration/gaia-central/rev/f6881029aca5
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Revert "Bug 946556 - [Music] Disable the play controls when using a bluetooth headset in a call"

This reverts commit a69025bfe657a07cca372369e0d4b83a442fba73.
Bumping manifests a=b2g-bump