src/arch: Remove unused <stdlib.h>

Change-Id: I79f065703b5249ca9630b06de7142bc52675076e
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32820
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/x86/mmap_boot.c

@@ -13,7 +13,6 @@
 
 #include <boot_device.h>
 #include <endian.h>
-#include <stdlib.h>
 
 /* The ROM is memory mapped just below 4GiB. Form a pointer for the base. */
 #define rom_base ((void *)(uintptr_t)(0x100000000ULL-CONFIG_ROM_SIZE))