ispsdk: Tidy up ov4689 sensor impletementation code.
1. Removed useless annotated code.
2. Removed redundant i2c operations funtions.
3. Fixed V4l2_DRIVERS & USE_LINUX_SYSTEM_STARTAND_I2C branches, removed VIRTUAL_IO_MAPPING branches.
4. Moved ADD_USLEEP_FOR_I2C_READ into i2c read functions.
5. Removed useless ModeRegs array.
Signed-off-by: Kevin.xie <kevin.xie@starfivetech.com>