Juno/vexpress Android kernel based on 3.18 version of Linaro Stable Kernel (LSK)

Changes in this version:

- Cherry-picked mailbox patches from upstream:
    commit 0cc67945ea59 ("mailbox: switch to hrtimer for tx_complete polling")
    commit 86e488adaab7 ("mailbox: arm_mhu: reduce txpoll_period from 10ms to 1 ms")
  These appear to mitigate Bug 1841 "CTS job fails on LCR-M" [1] and may
  also help hangs/crashes reported in other circumstances. However, the
  likelihood is that this is just masking underlying bugs in SCPI or
  mailbox code, which still needs investigation.
  [1] https://bugs.linaro.org/show_bug.cgi?id=1841

- Changed scpi clock-output-names in juno-base.dtsi for mali and i2s
  clocks to match the consumers, and removed redundant soc_i2sclk. This
  should not affect 3.18 kernel but were done to match requirements of
  latest kernel (4.3) which now uses these names in some circumstances
  for clock matching.