tree: Drop unused <halt.h>

Change-Id: Icd00f30a96c53f70babdcb8a77c4b6c2868619d8
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81820
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Yidi Lin <yidilin@google.com>

src/soc/mediatek/mt8186/rtc.c

@@ -6,7 +6,6 @@
  */
 
 #include <delay.h>
-#include <halt.h>
 #include <soc/rtc.h>
 #include <soc/rtc_common.h>
 #include <soc/mt6366.h>