Minor changes while pondering a camera interface

include/nuttx/spi/spi.h

@@ -354,6 +354,7 @@ enum spi_dev_e
   SPIDEV_FLASH,       /* Select SPI FLASH device */
   SPIDEV_ETHERNET,    /* Select SPI ethernet device */
   SPIDEV_DISPLAY,     /* Select SPI LCD/OLED display device */
+  SPIDEV_CAMERA,      /* Select SPI imaging device */
   SPIDEV_WIRELESS,    /* Select SPI Wireless device */
   SPIDEV_TOUCHSCREEN, /* Select SPI touchscreen device */
   SPIDEV_EXPANDER,    /* Select SPI I/O expander device */