src: include <assert.h> when appropriate

Change-Id: Ib843eb7144b7dc2932931b9e8f3f1d816bcc1e1a
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/26796
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: David Guckian

src/cpu/intel/hyperthreading/intel_sibling.c

@@ -17,7 +17,6 @@
 #include <device/device.h>
 #include <pc80/mc146818rtc.h>
 #include <smp/spinlock.h>
-#include <assert.h>
 
 #if CONFIG(PARALLEL_CPU_INIT)
 #error Intel hyper-threading requires serialized CPU init