Allow for one to write an individual byte of a 32-bit register when sending a read/write through the IOSF messaging system. Add PUNIT registers and fields for early sequencing. BUG=chrome-os-partner:23085 BRANCH=None TEST=Built and partially booted with changes that use PUNIT registers and individual byte en fields. Change-Id: I929fb5c51d805c55c478cab884e3572254987fc7 Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/171710 Reviewed-by: Duncan Laurie <dlaurie@chromium.org> Reviewed-on: http://review.coreboot.org/4859 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>