Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add support for frobbing Intel StrataFlash Protection Registers:
o add CFI_SUPPORT_STRATAFLASH compile option to enable support
o add new ioctls to get/set the factory and user/oem segments of the PR
and to get/set Protection Lock Register that fuses the user segment
o add #defines for bits in the status register
o update cfi_wait_ready to take an offset so it can be used to wait for
PR write completion and replace constants w/ symbolic names

Note: writing the user segment isn't correct; committing now to get review.

Sponsored by: Carlson Wireless
Reviewed by: imp, Chris Anderson

Fix copyright notice.

Add a driver for flash memory that implements to the Common Flash
Memory Interface (CFI). The flash memory can be read and written
to through /dev/cfi# and an ioctl() exists so processes can read
the query information.
The driver supports the AMD and Intel command set, though only
the AMD command has been tested.

Obtained from: Juniper Networks, Inc.