SUMMARY:
OV518 color is finally working! Lots of other small fixes too, including support
for the maximum possible OV518 frame rate (30 FPS @ 352x288, given sufficient
illumination). The ovfx2 driver is almost functional now too.


PER-FILE CHANGES:

ov511.c:
- OV518 color works, so enable it by default.
- Simplify sensor_set_light_freq()
- Force sensor's clock divider to 0 with OV518 (part 1 of color fixes)
- Disable OV518 U/V swap (part 2 of color fixes)
- Increase OV518's clock divider from 2 to 4 (part 3 of color fixes)
- Increase OV518 packet size to maximum. This required changes to the CBRs to
  prevent the internal buffers from overflowing. The framerate is only limited
  by the sensor now.
- Fix capture state machine in *move_data(). It was checking the wrong frame's
  status.
- Rename close() to release() to make it clear that it's *not* the converse of
  open()
- Remove redundant OV7620 init code from ov7xx0_configure(). I increased
  OV511_I2C_RETRIES and i2c_detect_tries to make up for this.

ov511.h:
- Remove some unused #defines and fix up some comments

ov6x30.c:
- Use initial register settings from the Windows driver for now. They will be
  merged with the existing settings eventually. (part 4 of color fixes)
- Use ov_write_mask on register 0x14 when selection CIF/QCIF, so that other bits
  aren't affected (part 5 of color fixes)
- Don't write register 0x13 after init, or color will break. Even writing the
  current value breaks it! (part 6 of color fixes)
- Hardcode clock divider to 0 for now, and remove "clock down" code. (part 7 of
  color fixes)

ovfx2.c:
- Remove some irrelevant OV511/OV518 junk
- Simplify sensor_set_light_freq()
- Switch default format to YUV422 for now (since it's closest to GBR422)
- Add a bunch of OV7620 register settings that are specific to this camera
- Add bulk submission code and completion handler
- Add frame parsing code (ovfx2_move_data())
- Rename close() to release() to make it clear that it's *not* the converse of
  open()
- Add simplified version of read() for debugging purposes
- Remove redundant OV7620 init code from ov7xx0_configure(). I increased
  OV511_I2C_RETRIES and i2c_detect_tries to make up for this.