msm: perf_defconfig: Enable CONFIG_CPUIDLE_MULTIPLE_DRIVERS

MSM8939 device has CPUs with different latencies. Enable
CONFIG_CPUIDLE_MULTIPLE_DRIVERS config to allow cpuidle
framework to use different drivers for different CPUs.

Change-Id: I646e23bb0da641aabda6a8be350f9ab45916258d
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>