libpayload;arch,cpu/x86: drop USE_MARCH_586 Kconfig option

Only the Intel Quark SoC selected this option and that SoC was dropped
in commit 531023285e ("soc/intel/quark: Drop support"), so drop this
Kconfig option too.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Ic4f1c7530cd8ac7a1945b1493a2d53a7904daa06
Reviewed-on: https://review.coreboot.org/c/coreboot/+/75473
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

payloads/libpayload/Kconfig

@@ -167,14 +167,6 @@ config BASE_ADDRESS
 
 endmenu
 
-config USE_MARCH_586
-	bool "Use march=586 qualifier to build"
-	default n
-	depends on ARCH_X86
-	help
-	  Allow a platform or processor to select to be compiled using
-	  the '-march=i586' option instead of the typical '-march=i686'
-
 menu "Standard Libraries"
 
 config LIBC