fw update: spi device code updater

This code updater is for updating spi flash devices.
It can for example update the host firmware on different server boards
and has following features:

- power down the host before update
- set mux gpios to access spi flash
- (very limited) communication with ME (Management Engine)
- use flashrom to utilize fw with IFD (Intel Flash Descriptor)
- otherwise directly write to the flash chip.

The behavior of this code updater can be configured via EM.

Tested: on Tyan S5549 Board

Change-Id: I27803b7fded71af2364c2f55fad841a410603dec
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/meson.options b/meson.options
index 605786d..b477342 100644
--- a/meson.options
+++ b/meson.options
@@ -133,3 +133,8 @@
     value: '/run/media/rwfs-alt/cow',
     description: 'The dir for alt-rwfs partition.',
 )
+
+option(
+    'code-updater-spi-device', type: 'feature', value: 'enabled',
+    description: 'enable update of spi device / host fw',
+)