Add INPUT_ANALOG to disconnect GPIO internally; fix qspi/uart/i2s/spi/sai to disconnect GPIO on *_disable()

Author: GrumpyOldPizza

cores/stm32l4/Arduino.h

@@ -51,6 +51,7 @@ extern "C"{
 #define OUTPUT          (0x1)
 #define INPUT_PULLUP    (0x2)
 #define INPUT_PULLDOWN  (0x3)
+#define INPUT_ANALOG    (0x4)
 
 #define PI 3.1415926535897932384626433832795
 #define HALF_PI 1.5707963267948966192313216916398

cores/stm32l4/stm32l4_wiring_digital.c

@@ -59,6 +59,11 @@ void pinMode( uint32_t ulPin, uint32_t ulMode )
 	stm32l4_gpio_pin_configure(g_APinDescription[ulPin].pin, (GPIO_PUPD_PULLDOWN | GPIO_OSPEED_MEDIUM | GPIO_OTYPE_PUSHPULL | GPIO_MODE_INPUT));
 	break ;
 
+    case INPUT_ANALOG:
+	// Set pin to analog mode
+	stm32l4_gpio_pin_configure(g_APinDescription[ulPin].pin, (GPIO_PUPD_NONE | GPIO_MODE_ANALOG));
+	break ;
+
     case OUTPUT:
 	// Set pin to output mode
 	stm32l4_gpio_pin_configure(g_APinDescription[ulPin].pin, (GPIO_PUPD_NONE | GPIO_OSPEED_MEDIUM | GPIO_OTYPE_PUSHPULL | GPIO_MODE_OUTPUT));