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

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https://hg.mozilla.org/integration/gaia-central/rev/8d7b64cbf47e
Author: Fernando Jiménez Moreno <ferjmoreno@gmail.com>
Desc: Merge pull request #12329 from ferjm/bug908117.ussdfromcontacts

Bug 908117: [B2G][dialer][tongxiao]Could not send out the USSD command w...

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https://hg.mozilla.org/integration/gaia-central/rev/981a9726818e
Author: Fernando Jiménez <ferjmoreno@gmail.com>
Desc: Bug 908117: [B2G][dialer][tongxiao]Could not send out the USSD command when the USSD number is saved in the contact. r=jmcantera