MAX31855: fix constructor param

Author: leonardocavagnis

src/utility/THERMOCOUPLE/MAX31855.cpp

@@ -38,7 +38,7 @@ const MAX31855Class::coefftable MAX31855Class::CoeffK[];
 const MAX31855Class::coefftable MAX31855Class::InvCoeffJ[];
 const MAX31855Class::coefftable MAX31855Class::InvCoeffK[];
 
-MAX31855Class::MAX31855Class(int cs, SPIClass& spi) :
+MAX31855Class::MAX31855Class(PinName cs, SPIClass& spi) :
   _cs(cs),
   _spi(&spi),
   _spiSettings(4000000, MSBFIRST, SPI_MODE0),

src/utility/THERMOCOUPLE/MAX31855.h

@@ -29,7 +29,7 @@
 
 class MAX31855Class {
 public:
-  MAX31855Class(int cs = 7, SPIClass& spi = SPI);
+  MAX31855Class(PinName cs = PI_0, SPIClass& spi = SPI);
 
   int begin();
   void end();