[Arista] Update kernel dependency from 4.9.0-9 to 4.9.0-12#58

lguohan merged 1 commit intolguohan:4.9.246lguohan/sonic-buildimage:4.9.246from

Staphylo:201811-kernel-4.9.0-12Staphylo/sonic-buildimage:201811-kernel-4.9.0-12Copy head branch name to clipboard