arch/x86/Kconfig: drop HPET_ADDRESS_OVERRIDE

Commit b433d26ef1 (arch/x86: Define
HPET_ADDRESS_OVERRIDE) added this Kconfig option and referenced the
via/cx700 chipset which has been dropped before the 4.9 release. No SoC
in the current tree selects HPET_ADDRESS_OVERRIDE and all SoCs have
their HPET mapped at 0xfed00000, so drop this unused and no longer
needed Kconfig option.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I4021ed6f84473c7a9223323fc8aa5d3f935d8084
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62276
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/x86/Kconfig

@@ -191,12 +191,9 @@ config CMOS_DEFAULT_FILE
 	default "src/mainboard/\$(MAINBOARDDIR)/cmos.default"
 	depends on HAVE_CMOS_DEFAULT
 
-config HPET_ADDRESS_OVERRIDE
-	def_bool n
-
 config HPET_ADDRESS
 	hex
-	default 0xfed00000 if !HPET_ADDRESS_OVERRIDE
+	default 0xfed00000
 
 config C_ENV_BOOTBLOCK_SIZE
 	hex