Fix compiler warning

diff --git a/OLEDDisplay.cpp b/OLEDDisplay.cpp
index dca2ad1..35eb456 100644
--- a/OLEDDisplay.cpp
+++ b/OLEDDisplay.cpp
@@ -941,15 +941,6 @@ size_t OLEDDisplay::write(uint8_t c) {
   return 1;
 }
 
-size_t OLEDDisplay::write(const char* str) {
-  if (str == NULL) return 0;
-  size_t length = strlen(str);
-  for (size_t i = 0; i < length; i++) {
-    write(str[i]);
-  }
-  return length;
-}
-
 #ifdef __MBED__
 int OLEDDisplay::_putc(int c) {
 
diff --git a/OLEDDisplay.h b/OLEDDisplay.h
index 23e6845..07cb9a2 100644
--- a/OLEDDisplay.h
+++ b/OLEDDisplay.h
@@ -330,7 +330,6 @@ class OLEDDisplay : public Stream {
 
     // Implement needed function to be compatible with Print class
     size_t write(uint8_t c);
-    size_t write(const char* s);
 
     // Implement needed function to be compatible with Stream class
 #ifdef __MBED__