Use __asm__("nop") in the loop-based delays.

Since we recently switched from -O0 to -Os, an increase in the loop count
as well as the addition of __asm__("nop") is required (so that the loop
doesn't get optimized/removed).
The real fix is to add a proper timer-based delay function, of course.

Also, fix a bunch of cosmetic issues and typos.

examples/stm32/obldc/pwmleds/pwmleds.c

@@ -454,7 +454,8 @@ int main(void)
 			d3 =- 1;
 		if (j3 == 19)
 			j3 = 20;
-		for (i = 0; i < 15000; i++) __asm("nop");
+		for (i = 0; i < 15000; i++)
+			__asm__("nop");
 		j++;
 		if (j == 100) {
 			j = 0;