soc/amd/common: Clean up file includes

Remove unnecessary header file includes.

Change-Id: I9ad9e86f3c75903e278e898602caec04351f64b6
Signed-off-by: Frank Vibrans <frank.vibrans@scarletltd.com>
Reviewed-on: https://review.coreboot.org/21989
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/amd/common/block/psp/psp.c

@@ -14,8 +14,6 @@
  */
 
 #include <arch/io.h>
-#include <delay.h>
-#include <cbmem.h>
 #include <timer.h>
 #include <device/pci_def.h>
 #include <console/console.h>