Fix missing DSP instruction alternates on Teensy LC

utility/dspinst.h

 	asm volatile("smmul %0, %1, %2" : "=r" (out) : "r" (a), "r" (b));
 	return out;
 #elif defined(KINETISL)
-	return 0; // TODO....
+	return ((int64_t)a * (int64_t)b) >> 32;
 #endif
 }
 
 	asm volatile("smmulr %0, %1, %2" : "=r" (out) : "r" (a), "r" (b));
 	return out;
 #elif defined(KINETISL)
-	return 0; // TODO....
+	return (((int64_t)a * (int64_t)b) + 0x8000000) >> 32;
 #endif
 }
 
 	asm volatile("smmlar %0, %2, %3, %1" : "=r" (out) : "r" (sum), "r" (a), "r" (b));
 	return out;
 #elif defined(KINETISL)
-	return 0; // TODO....
+	return sum + ((((int64_t)a * (int64_t)b) + 0x8000000) >> 32);
 #endif
 }
 
 	asm volatile("smmlsr %0, %2, %3, %1" : "=r" (out) : "r" (sum), "r" (a), "r" (b));
 	return out;
 #elif defined(KINETISL)
-	return 0; // TODO....
+	return sum - ((((int64_t)a * (int64_t)b) + 0x8000000) >> 32);
 #endif
 }