ARM: vfp: initialize vfp driver before cpufreq

After the below commit, cpufreq driver is initialized before vfp_init().
Commit 78727d2 ("msm: cpufreq: Initialize cpufreq driver early at boot")

Because of this, CPUs can enter idle during vfp_init().
The following deadlock situation can be occurred.

CPU2/3:
cpu_idle()
cpu_pm_enter()
read_lock(&cpu_pm_notifier_lock)

CPU0:
vfp_init()
cpu_pm_register_notifier()
write_lock_irqsave(&cpu_pm_notifier_lock, flags)

For avoid this problem, move vfp_init to rootfs_initcall.

Change-Id: Ib8a29f1ecfd19d187d2532d8a816da9519cdcd70
Signed-off-by: Bongkyu Kim <bongkyu.kim@lge.com>