ipmi: Add SMBus interface driver (SSIF)

This patch adds the SMBus interface to the IPMI driver.

Signed-off-by: Corey Minyard <minyard@acm.org>
 Documentation/IPMI.txt       |   32
 drivers/char/ipmi/Kconfig    |   11
 drivers/char/ipmi/Makefile   |    1
 drivers/char/ipmi/ipmi_smb.c | 1737 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 1769 insertions(+), 12 deletions(-)