Update W55RP20 example for proper CS pin (#2906)

Fixes #2903

Author: earlephilhower

libraries/lwIP_w55rp20/examples/WiFiClient-W55RP20/WiFiClient-W55RP20.ino

@@ -8,7 +8,7 @@
 const char* host = "djxmmx.net";
 const uint16_t port = 17;
 
-Wiznet55rp20lwIP eth(1 /* chip select */);
+Wiznet55rp20lwIP eth(20 /* chip select */);
 
 void setup() {
   Serial.begin(115200);

libraries/lwIP_w55rp20/src/utility/w55rp20.h

@@ -51,7 +51,7 @@ class Wiznet55rp20 {
         Constructor that uses the default hardware SPI pins
         @param cs the Arduino Chip Select / Slave Select pin (default 10)
     */
-    Wiznet55rp20(int8_t cs = SS, SPIClass& spi = SPI, int8_t intr = -1);
+    Wiznet55rp20(int8_t cs = WIZNET_PIO_SPI_CS_PIN, SPIClass& spi = SPI, int8_t intr = -1);
     //Wiznet55rp20();
 
     /**