Update git submodules

Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Merge "Qemu: Mechanism to pass extra qemu cpu features and pin vCPU threads"
  - Qemu: Mechanism to pass extra qemu cpu features and pin vCPU threads

    JIRA: VSPERF-510

    This patch is used to implement the mechanism to pass extra qemu
    cpu options required to achieve better results/performance. Also
    used to implement a mechanism to pin the vCPU threads to another
    pCPU core which helps in reducing the noise from housekeeping
    thread and packet loss.

    Change-Id: Ic40fd47d7c4f5556f7e240c6ca671a0535d06ece
    Signed-off-by: Gundarapu Kalyan Reddy <reddyx.gundarapu@intel.com>