sb/nvidia/mcp55: Fix P_state generation

amd_generate_powernow is never called by in lpc_slave_ops.
Move it to lpc_ops like on all other AMD southbridges.

TESTED on Gigabyte ga-m57sli-s4

Change-Id: I7db036e681d591a19e15dd3eaafb88b72a41bea1
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/17977
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
1 file changed