fix SPI speed calculation @160Mhz Clock

Author: Links2004

hardware/esp8266com/esp8266/libraries/SPI/SPI.cpp

@@ -121,14 +121,14 @@ void SPIClass::setBitOrder(uint8_t bitOrder) {
  * @return
  */
 static uint32_t ClkRegToFreq(spiClk_t * reg) {
-    return (F_CPU / ((reg->regPre + 1) * (reg->regN + 1)));
+    return (SPI_MAX_SPEED / ((reg->regPre + 1) * (reg->regN + 1)));
 }
 
 void SPIClass::setFrequency(uint32_t freq) {
     static uint32_t lastSetFrequency = 0;
     static uint32_t lastSetRegister = 0;
 
-    if(freq >= F_CPU) {
+    if(freq >= SPI_MAX_SPEED) {
         setClockDivider(0x80000000);
         return;
     }
@@ -164,7 +164,7 @@ void SPIClass::setFrequency(uint32_t freq) {
         reg.regN = calN;
 
         while(calPreVari++ <= 1) { // test different variants for Pre (we calculate in int so we miss the decimals, testing is the easyest and fastest way)
-            calPre = (((F_CPU / (reg.regN + 1)) / freq) - 1) + calPreVari;
+            calPre = (((SPI_MAX_SPEED / (reg.regN + 1)) / freq) - 1) + calPreVari;
             if(calPre > 0x1FFF) {
                 reg.regPre = 0x1FFF; // 8191
             } else if(calPre <= 0) {

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

@@ -45,6 +45,8 @@
 #define SPI_CLOCK_DIV64 	0x04fc1001 //250 KHz
 #endif
 
+#define SPI_MAX_SPEED      (80000000L)
+
 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