amdk8/amdfam10: Use CAR_GLOBAL for sysinfo

This gets rid of the somewhat unstructured placement of AMD's
sysinfo structure in CAR.
We used to carve out some CAR space using a Kconfig variable,
and then put sysinfo there manually (by "virtue" of pointer magic).

Now it's a variable with the CAR_GLOBAL qualifier, and build
system magic.

For this, the following steps were done (but must happen together
since the intermediates won't build):
- Add new CAR_GLOBAL sysinfo_car
- point all sysinfo pointers to sysinfo_car instead of GLOBAL_VAR
- remove DCACHE_RAM_GLOBAL_VAR_SIZE
  - from CAR setup (no need to reserve the space)
  - commented out code (that was commented out for years)
  - only copy sizeof(sysinfo) into RAM after ram init, where
    before it copied the whole GLOBAL_VAR area.
  - from Kconfig

Change-Id: I3cbcccd883ca6751326c8e32afde2eb0c91229ed
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/1887
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Marc Jones <marcj303@gmail.com>

src/mainboard/ibm/e325/Kconfig

@@ -28,10 +28,6 @@ config DCACHE_RAM_SIZE
 	hex
 	default 0x1000
 
-config DCACHE_RAM_GLOBAL_VAR_SIZE
-	hex
-	default 0x0
-
 config APIC_ID_OFFSET
 	hex
 	default 0x0

src/mainboard/ibm/e326/Kconfig

@@ -28,10 +28,6 @@ config DCACHE_RAM_SIZE
 	hex
 	default 0x1000
 
-config DCACHE_RAM_GLOBAL_VAR_SIZE
-	hex
-	default 0x0
-
 config APIC_ID_OFFSET
 	hex
 	default 0x0