linux: Update to v4.2.1-openpower1

This brings in the 4.2.1 stable release, and the accraid RAID driver for
PMC-Sierra RAID  on Habanero.

The RAID driver is submitted upstream to the linux-scsi mailing list,
but is not yet in a tree.

The stable release brings in a few commits that are of interest to
OpenPower platforms:

 94d718d024e xfs: return errors from partial I/O failures to files
 2937b784b19 xfs: Fix file type directory corruption for btree directories
 95310b79776 libxfs: readahead of dir3 data blocks should use the read verifier
 0a3b19cef4f sched: Fix cpu_active_mask/cpu_online_mask race

Signed-off-by: Joel Stanley <joel@jms.id.au>
25 files changed