pnp: Allow setting of misc register 0xf4 in device tree

Change-Id: I602f970e0ee2fd634a74fd4c25358c2e78ca58f9
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: https://chromium-review.googlesource.com/179536
Commit-Queue: Stefan Reinauer <reinauer@chromium.org>
Tested-by: Stefan Reinauer <reinauer@chromium.org>
Reviewed-by: Shawn Nematbakhsh <shawnn@chromium.org>
(cherry picked from commit 02b0583e632f1ba53557f8cfe4293ad4ed29ff4d)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6910
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>