SPI._read_byte() is still used when SPI._read_burst() is defined

[Frovu]

In w5500.c WIZCHIP_READ() on line ret = WIZCHIP.IF.SPI._read_byte(); function _read_byte() is called even if _read_burst() is defined.

While reading general logic of these WIZCHIP_READ/WRITE functions I assumed that if user defines burst variants of SPI operation one byte variants are not required anymore, but this only mentioned line forces me to implement _read_byte() function explicitly, however in my case it's essentially same as _read_burst(&ret, 1). (I use this driver with STM32 HAL)

Probably it's not an issue and maybe in other implementations using read byte would be faster than read burst (1), but imo it would be nice to allow user to not define one byte callback functions if they defined burst variants already.

Like:

if (!WIZCHIP.IF.SPI._read_burst) {
    ret = WIZCHIP.IF.SPI._read_byte();
} else {
    WIZCHIP.IF.SPI._read_burst(&ret, 1);
}