stm32/boards/NUCLEO_L452RE: Standardize pin names.

But keep the CNX_Y notation to prevent breaking code.

Signed-off-by: Asensio Lorenzo Sempere <asensio.aerospace@gmail.com>

ports/stm32/boards/NUCLEO_L452RE/pins.csv

@@ -84,3 +84,55 @@ SWDIO,PA13
 SWCLK,PA14
 USER_B1,PC13
 LED_GREEN,PA5
+PA0,PA0
+PA1,PA1
+PA2,PA2
+PA3,PA3
+PA4,PA4
+PA5,PA5
+PA6,PA6
+PA7,PA7
+PA8,PA8
+PA9,PA9
+PA10,PA10
+PA11,PA11
+PA12,PA12
+PA13,PA13
+PA14,PA14
+PA15,PA15
+PB0,PB0
+PB1,PB1
+PB2,PB2
+PB3,PB3
+PB4,PB4
+PB5,PB5
+PB6,PB6
+PB7,PB7
+PB8,PB8
+PB9,PB9
+PB10,PB10
+PB11,PB11
+PB12,PB12
+PB13,PB13
+PB14,PB14
+PB15,PB15
+PC0,PC0
+PC1,PC1
+PC2,PC2
+PC3,PC3
+PC4,PC4
+PC5,PC5
+PC6,PC6
+PC7,PC7
+PC8,PC8
+PC9,PC9
+PC10,PC10
+PC11,PC11
+PC12,PC12
+PC13,PC13
+PC14,PC14
+PC15,PC15
+PD2,PD2
+PH0,PH0
+PH1,PH1
+PH3,PH3