soc/amd/stoneyridge: Enable early cbmem

Add a memmap file with a cbmem_top() function.  Remove the
LATE_CBMEM_INIT, allowing the default of EARLY.  Remove calls
to the late-only set_top_of_ram() function.

Change-Id: I11ad7190031c912642a7312f2fc6f792866288b7
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/19751
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>

src/soc/amd/stoneyridge/Kconfig

@@ -35,7 +35,6 @@ config CPU_SPECIFIC_OPTIONS
 	select HAVE_USBDEBUG_OPTIONS
 	select HAVE_HARD_RESET
 	select LAPIC_MONOTONIC_TIMER
-	select LATE_CBMEM_INIT
 	select SPI_FLASH if HAVE_ACPI_RESUME
 	select TSC_SYNC_LFENCE
 	select SOC_AMD_COMMON