staging: most: rename DIMCB_IoWrite to dimcb_io_write

This patch renames DIMCB_IoWrite to dimcb_io_write to avoid camelcase
found by checkpatch.

CHECK: Avoid CamelCase: <DIMCB_IoWrite>
FILE: drivers/staging/most/hdm-dim2/dim2_hal.c:154:

Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>