[coreboot] [patch] correct off-by-one in pre-rev-F model F powernow code

[Jonathan A. Kollasch]

Correct off-by-one problem in AMD pre-rev-F model-F PowerNow code.
With this change the last P-state entry of the last CPU in the table
is successfully conveyed into the SSDT.

Signed-off-by: Jonathan Kollasch 
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