cpuidle: don't disable cpuidle when entering suspend

cpuidle was disabled while entering suspend as part of commit
8651f97b in order to work around some
ACPI bugs. However, there's no reason to do this on modern
platforms. Leaving cpuidle enabled can result in improved power
consumption if dpm_resume_noirq runs for a significant time.

Change-Id: Ie182785b176f448698c0264eba554d1e315e8a06