small spi fix

firmware/shared/spi.c

@@ -27,11 +27,6 @@ funptr_t spi_proto_funcs[] = {
  * currently alpha, uses interrupts, single master/single slave operation
  */
 
-uint8_t * volatile spi_writeptr;
-uint8_t * volatile spi_readptr;
-uint8_t volatile spi_writelen;
-uint8_t volatile spi_readlen;
-uint8_t spi_readbuf[SPI_READBUF_LEN];