staging: sm750fb: Edit CamelCase in local variables

Edit CamelCase in local variables across 4 files:
- sm750fb/ddk750_chip.c
- sm750fb/ddk750_chip.h
- sm750fb/ddk750_dvi.c
- sm750fb/ddk750_sii164.c
to comply with the coding style. Also edit associated comments
accordingly.
Issue found with Checkpatch.

Signed-off-by: Nishka Dasgupta <nishka.dasgupta@yahoo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>