Bumping gaia.json for 1 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/6ce2fe088a11
Author: Arthur Chen <crh0716@gmail.com>
Desc: Revert "Bug 903232 - Show only gsm options by default"

This reverts commit ad7c92b4d02477d9096fed03963f9a2d8717a5a4.