BLACK_F407ZX: invert PF9 and PF10 in digitalPin[]

Invert PF9 and PF10 in digitalPin[] to match their definition in
variant.h
Fixes forum issue:
https://www.stm32duino.com/viewtopic.php?p=6652#p6652

Signed-off-by: Alexandre Bourdiol <alexandre.bourdiol@st.com>

Author: ABOSTM

variants/STM32F4xx/F407Z(E-G)Tx_F417Z(E-G)Tx/variant_BLACK_F407ZX.cpp

@@ -78,7 +78,7 @@ const PinName digitalPin[] = {
   /*PF_10,*/PC_0,   // PF_10: Moved to allow contiguous analog pins
   PF_8, /*PF_9,*/ // PF_9: Moved to allow contiguous analog pins
   PF_6,   PF_7,
-  PF_10,  PF_9,   // PF_10: LED D2, PF_9: LED D1 (active low)
+  PF_9,   PF_10,  // PF_10: LED D2, PF_9: LED D1 (active low)
   PF_4,   PF_5,
   PF_2,   PF_3,
   PF_0,   PF_1,