pinMode(MISO, SPECIAL); ///< GPIO12
pinMode(MOSI, SPECIAL); ///< GPIO13
You are right. In gpio_MCP23S17.h is the configuration for arduino.
You must take the Spi.h for ESP8266 in:
C:\Users\ich\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\SPI
Change the wiring in your schematic. You have the mcp23s17 wired to the intern Flash-chip ..