alcd_backlight prototype changed
_ioctl: ioclt_buf_t type changed to void*

We switched to generic pointer. All files are updated.
sd_spi: The driver is operational and tested with my cards (closes #6)

- Tested with spi bit-banging driver and stm32_spi driver
- The driver links with spi using:
   must:
   1) spi (void*) data struct (NULL for simple implementations)
   2) spi_rw()
   3) spi_ioctl()
   4) low-level chip_select output function
   optional:
   5) low-level chip_detect input function
   6) low-level power-on/off output function
   7) low-level write_protect input function
- The driver supports multiple drives (at compile time)
spi_bb: A SPI bit-banging driver added to toolbox

- Supports drv_status_en type
- Supports CPOL, CPHA
- SS can be hadled inside or outside of the driver.