northbridge/amd/amdfam10: Add ability to set maximum P-state limit

Under specific circumstances, for instance in low power or fanless
machines, it may be useful to cap the maximum P-state of the CPU.

Allow the maximum CPU P-state to be set via an NVRAM option.

Change-Id: Ifdbb1ad11a856f855c59702ae0ee99e95b08520e
Signed-off-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Reviewed-on: http://review.coreboot.org/11985
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins)
1 file changed