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

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https://hg.mozilla.org/integration/gaia-central/rev/bbc80670c2bc
Author: Greg Weng <snowmantw@gmail.com>
Desc: Merge pull request #20540 from snowmantw/issue970824

Bug 970824 - [LockScreen][System] Stop directly use 'lockScreen.locked'

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https://hg.mozilla.org/integration/gaia-central/rev/51c8596dfc6e
Author: Greg Weng <snowmantw@gmail.com>
Desc: Bug 970824 - [LockScreen][System] Stop directly use 'lockScreen.locked'
Bumping manifests a=b2g-bump