add back SPI_CLOCK_DIVx defines may needed by some library

Note:
better use SPI.setFrequency()

Author: Links2004

hardware/esp8266com/esp8266/libraries/SPI/SPI.h

@@ -24,6 +24,25 @@
 #include <Arduino.h>
 #include <stdlib.h>
 
+// This defines are not representing the real Divider of the ESP8266
+// the Defines match to an AVR Arduino on 16MHz for better compatibility
+#if F_CPU == 80000000L
+#define SPI_CLOCK_DIV2 		0x00101001 //8 MHz
+#define SPI_CLOCK_DIV4 		0x00241001 //4 MHz
+#define SPI_CLOCK_DIV8 		0x004c1001 //2 MHz
+#define SPI_CLOCK_DIV16 	0x009c1001 //1 MHz
+#define SPI_CLOCK_DIV32 	0x013c1001 //500 KHz
+#define SPI_CLOCK_DIV64 	0x027c1001 //250 KHz
+#define SPI_CLOCK_DIV128 	0x04fc1001 //125 KHz
+#else
+#define SPI_CLOCK_DIV2 		0x00241001 //8 MHz
+#define SPI_CLOCK_DIV4 		0x004c1001 //4 MHz
+#define SPI_CLOCK_DIV8  	0x009c1001 //2 MHz
+#define SPI_CLOCK_DIV16 	0x013c1001 //1 MHz
+#define SPI_CLOCK_DIV32 	0x027c1001 //500 KHz
+#define SPI_CLOCK_DIV64 	0x04fc1001 //250 KHz
+#endif
+
 const uint8_t SPI_MODE0 = 0x00; ///<  CPOL: 0  CPHA: 0
 const uint8_t SPI_MODE1 = 0x01; ///<  CPOL: 0  CPHA: 1
 const uint8_t SPI_MODE2 = 0x10; ///<  CPOL: 1  CPHA: 0