3rdparty/blobs: Update submodule, SNB improvements

The sandybridge systemagent-r6 blob is modified:
- To be more flexible about the location of the stack w.r.t. the heap
- Place the MRC pool right below the MRC_VAR region
- to work with the same DCACHE_RAM_BASE from the native raminit (could
  make the CAR linker symbols easily compatible if desired)

This allows CAR setup compatibility between mrc.bin and native
bootpath and also allows for BIOS/memory mappeds region larger than
8MB.

This changes the semantics of CONFIG_DACHE_RAM_MRC_VAR_SIZE to also
include the pool on top of MRC_VAR region.

TESTED on T520 (boots and resumes from S3 with mrc.bin).

Change-Id: I17d240656575b69a24718d90e4f2d2b7339d05a7
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33228
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/x86/car.ld

@@ -91,13 +91,6 @@
 	_car_global_end = .;
 	_car_relocatable_data_end = .;
 
-#if CONFIG(NORTHBRIDGE_INTEL_SANDYBRIDGE) && !CONFIG(USE_NATIVE_RAMINIT)
-	. = ABSOLUTE(0xff7e1000);
-	_mrc_pool = .;
-	. += 0x5000;
-	_emrc_pool = .;
-#endif
-
 #if !CONFIG(C_ENVIRONMENT_BOOTBLOCK)
 	_car_stack_start = .;
 	_car_stack_end = _car_region_end;