msm8960-perf_defconfig: configure out wfd video driver

This driver seems to oops upon being opened if it fails to find its
firmware. The log looks something like the following:

  wfd: Failed to load video encoder firmware: 1
  mdp4_writeback_terminate called without stopping
  Unable to handle kernel NULL pointer dereference at virtual address 0000000d
  ....
  [<c0219a94>] (do_sys_open+0xf4/0x174) from [<c0105ff4>] (__sys_trace_return+0x0/0x2c)

Configure it out for now rather than fix the bug.

Move an ifdef to avoid a forbidden warning.
msm8960-perf_defconfig: configure in DEVTMPFS and AUTOFS4 for systemd
Packaging: add changelog entry for 3.0.21-12374-gcae2925-4