AMD Persimmon: Use SPD read code from F14 wrapper

Changes:
 - Get rid of the persimmon mainboard specific code which has been
   moved into the wrapper as a platform generic function in change
   http://review.coreboot.org/#/c/2497/
   AMD f14: Add SPD read functions to wrapper code

 - Move DIMM addresses into devicetree.cb

 - Add the ASF init that used to be in the SPD read code into
   mainboard_enable()

Notes:
 - The DIMM reads only happen in romstage, so the function is not
   available in ramstage.  Point the read-SPD callback to a generic
   function in ramstage.

Change-Id: I5f017dbb8dee5a09ec19734a6069ff9b71a6ab50
Signed-off-by: Martin Roth <martin.roth@se-eng.com>
Reviewed-on: http://review.coreboot.org/2500
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-by: Jens Rottmann <JRottmann@LiPPERTembedded.de>
Reviewed-by: Marc Jones <marc.jones@se-eng.com>
6 files changed