arch/x86: Drop Kconfig AP_SIPI_VECTOR

This was used to check romcc-built bootblock and romstage
agree about the location of 16-bit entrypoint. There was
no need to customize it as bootblock size requirement did
not grow. Just check for a fixed location at 4 GiB - 4 KiB.

With C_ENVIRONMENT_BOOTBLOCK we can have a proper symbol
for the purpose, since it appears in the same compilation
unit. It will adjust if C_ENV_BOOTBLOCK_SIZE changes.

Change-Id: I93f3c37e78ba587455c804de8c57e7e06832a81f
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/30854
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/cpu/Kconfig

@@ -42,12 +42,6 @@ config SMP
 	  This option is used to enable certain functions to make coreboot
 	  work correctly on symmetric multi processor (SMP) systems.
 
-config AP_SIPI_VECTOR
-	hex
-	default 0xfffff000
-	help
-	  This must equal address of ap_sipi_vector from bootblock build.
-
 config	MMX
 	bool
 	help