AGESA fam12 fam14 fam15: Declare local callouts static

Change-Id: I2ff70cafdd808a235ed4f0663e182d306f493c7e
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5685
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
17 files changed