Staging: sm750fb: Rename ddk750_setModeTiming

Staging: sm750fb: Rename ddk750_setModeTiming

Rename function ddk750_setModeTiming to ddk750_set_mode_timing. This
patch affects three files as the function is imported to other external
files.

This follows snakecase naming convention and ensures a consistent naming
style throughout the file. Issue found by checkpatch.

Mutes the following checkpatch error:
CHECK:Avoid CamelCase: <ddk750_setModeTiming>

Signed-off-by: Dorcas AnonoLitunya <anonolitunya@gmail.com>
Link: https://lore.kernel.org/r/20231016201434.7880-6-anonolitunya@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>