media: exynos4-is: Fix kernel-doc entries in fimc-is.h

Fixes scripts/kernel-doc warnings:

fimc-is.h:286: warning: Function parameter or member 'fw' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'memory' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'f_w' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'isp' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'sensor' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'setfile' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'ctrl_handler' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'irq' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'sensor_index' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'i2h_cmd' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'h2i_cmd' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'fd_header' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'config' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'config_index' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'is_p_region' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'is_dma_p_region' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'is_shared_region' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'af' not described in 'fimc_is'
fimc-is.h:286: warning: Function parameter or member 'debugfs_entry' not described in 'fimc_is'

The f_w field is unused so remove it.

Reported-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>