simple_plug: A new hotplug driver to replace mpdecision

Change-Id: Ie3424d4a44256a8e79cc845bba363b23e52e2706

Conflicts:
	arch/arm/mach-msm/Kconfig
ghost: Enable simple_plug hotplug driver

Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>