padata/pcrypt: cleanups

This patchset contains the following changes:

1. padata - Rename padata_alloc functions to not export underlined functions.

2. padata - Rearrange set_cpumask functions to have proper locking for all these functions and to avoid to export underlined functions.

3. padata - Pass the padata cpumasks to the cpumask_change_notifier chain, so users can access them without the need of a padata_get_cpumask function.

4. pcrypt - Rename the stuct pcrypt_instance. An instance refers usually to a crypto instance in the crypto-layer, the struct pcrypt_instance is not related to a crypto instance, so we rename it.

5. pcrypt - Update pcrypt cpumask acording to the padata cpumask notifier. The padata cpumask change notifier passes a padata_cpumask to the notifier chain, so we use this to update the pcrypt cpumask.

6. padata - Remove padata_get_cpumask. This function is a bit error prone because the cpumask can change at any time, so we can't be sure to get the right cpumask from that function.

7. padata - Update the API documentation.

Steffen