i2c, soft-i2c: switch to new multibus/multiadapter support

- added to soft_i2c driver new multibus/multiadpater support
- adapted all config files, which uses this driver

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>