arch/x86/Kconfig: Drop obsolete fixed ramstage symbols

On x86 ramstage is always relocated at runtime in cbmem so there is no
need to have this configurable in Kconfig.

Change-Id: I01b2335d0b82bea8f885ee5ca9814351bbf2aa3c
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63215
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/picasso/Kconfig

@@ -207,10 +207,6 @@ config VERSTAGE_SIZE
 	  Sets the size of DRAM allocation for verstage in linker script if
 	  running as a separate stage on x86.
 
-config RAMBASE
-	hex
-	default 0x10000000
-
 config ECAM_MMCONF_BASE_ADDRESS
 	default 0xF8000000