AMD northbridge: copy TOP_MEM and TOP_MEM2 for distribution

Take a copy of BSP CPU's TOP_MEM and TOP_MEM2 MSRs to be distributed
to AP CPUs and factor out the debugging info from setup_uma_memory().

Change-Id: I1acb4eaa3fe118aee223df1ebff997289f5d3a56
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/1387
Tested-by: build bot (Jenkins)
Reviewed-by: Zheng Bao <zheng.bao@amd.com>
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

src/include/cpu/amd/mtrr.h

@@ -39,6 +39,11 @@
 
 #if !defined(__PRE_RAM__) && !defined(__ASSEMBLER__)
 void amd_setup_mtrrs(void);
+
+/* To distribute topmem MSRs to APs. */
+void setup_bsp_ramtop(void);
+uint64_t bsp_topmem(void);
+uint64_t bsp_topmem2(void);
 #endif
 
 #endif /* CPU_AMD_MTRR_H */