Bumping gaia.json for 1 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/ef5b991b016d
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Merge pull request #12741 from jaoo/923161

Bug 923161 - Emergency calls not performed with some no-line SIM cards. r=etienne(cherry picked from commit 0fff8ad020a1934cae557155c951d73fb0887b8f)