Disable pull-up/pull-down when setting pin as input (earlephilhower#332)

In `pinMode()` I think it would be better to call `gpio_disable_pulls()` on the ulPin when ulMode == INPUT.
Adding `gpio_disable_pulls(RP_PIN);` after `pinMode(RP_PIN, INPUT);` solves the issue.

Author: giampiero7

cores/rp2040/wiring_digital.cpp

@@ -28,6 +28,7 @@ extern "C" void pinMode(pin_size_t ulPin, PinMode ulMode) {
     case INPUT:
         gpio_init(ulPin);
         gpio_set_dir(ulPin, false);
+        gpio_disable_pulls(ulPin);
         break;
     case INPUT_PULLUP:
         gpio_init(ulPin);