southbridge/hudson: Remove unused function set_sm_enable_bits()

This function isn't used on hudson, and seems to be copy-paste from
older southbridges. It is used in sb700 to enable or disable certain
PCI devices. On hudson, these configuration bits are moved to the PM
space.

Change-Id: I9b967a2d0a5dddc8341204dadeed90460251915c
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/5513
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@gmail.com>