PM / Domains: Allocate memory outside domain locks

In preparation for supporting IRQ-safe domains, allocate domain data
outside the domain locks. These functions are not called in an atomic
context, so we can always allocate memory using GFP_KERNEL. By
allocating memory before the locks, we can safely lock the domain using
spinlocks instead of mutexes.

Reviewed-by: Kevin Hilman <khilman@linaro.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>