Missing EXTI ports and flag numbers for F4

(Also missing for forthcoming L1)

include/libopencm3/stm32/exti.h

@@ -53,6 +53,9 @@
 #define EXTI17				(1 << 17)
 #define EXTI18				(1 << 18)
 #define EXTI19				(1 << 19)
+#define EXTI20				(1 << 20)
+#define EXTI21				(1 << 21)
+#define EXTI22				(1 << 22)
 
 /* Trigger types */
 typedef enum trigger_e {

lib/stm32/f4/exti.c

@@ -127,6 +127,12 @@ void exti_select_source(u32 exti, u32 gpioport)
 	case GPIOG:
 		bits = 0x9;
 		break;
+	case GPIOH:
+		bits = 0x8;
+		break;
+	case GPIOI:
+		bits = 0x7;
+		break;
 	}
 
 	/* Ensure that only valid EXTI lines are used. */