drivers/intel/ish: Include stdbool.h to identify bool type

When the concerned chip.h file is included in a source file, it causes
compilation error saying unknown type name bool. Fix it by including the
stdbool.h file in the chip.h file.

BUG=None
TEST=Build Brox by including the chip.h file in one of the source files.

Change-Id: I4159e2c281c3e89dc45555ce38ad8637a3bf8587
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81417
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Shelley Chen <shchen@google.com>

src/drivers/intel/ish/chip.h

@@ -3,6 +3,8 @@
 #ifndef __DRIVERS_INTEL_ISH_CHIP_H__
 #define __DRIVERS_INTEL_ISH_CHIP_H__
 
+#include <stdbool.h>
+
 /*
  * Intel Integrated Sensor Hub (ISH)
  */