Update Sd2PinMap.h

Line 20 caused bugs on ESP32 boards. Adding the following code fixes the bug and allows use on Espressif based boards. The bug was found using Platformio on VSCode.

Author: alejandrotovar9

src/utility/Sd2PinMap.h

@@ -17,7 +17,7 @@
    along with the Arduino SdFat Library.  If not, see
    <http://www.gnu.org/licenses/>.
 */
-#if defined(__arm__) // Arduino Due Board follows
+#if defined(__arm__) || defined(__XTENSA__) || defined(ESP32) // This line allows use on Espressif ESP32 boards
 
 #ifndef Sd2PinMap_h
   #define Sd2PinMap_h