fix LCD build for devboard

src/nrf52/UC1701Spi.cpp

@@ -36,11 +36,13 @@ class UC1701Spi : public OLEDDisplay
 };
 
 #include "variant.h"
+
+#ifdef ERC12864_CS
 #include <UC1701.h>
 static UC1701 lcd(PIN_SPI_SCK, PIN_SPI_MOSI, ERC12864_CS, ERC12864_CD);
 
-
-void testLCD() {
+void testLCD()
+{
     // PCD8544-compatible displays may have a different resolution...
     lcd.begin();
 
@@ -48,3 +50,4 @@ void testLCD() {
     lcd.setCursor(0, 0);
     lcd.print("Hello, World!");
 }
+#endif