media: atomisp: remove polling_mode and subscr_index

media: atomisp: remove polling_mode and subscr_index

This patch removes polling_mode and subscr_index from
`struct virtual_input_system_stream_s` as well as its usage [1]. Note
that for subscr_index, only the definition were removed because it was
not used anywhere.

[1] added on updating css version to irci_master_20150701_0213
    https://raw.githubusercontent.com/intel/ProductionKernelQuilts/cht-m1stable-2016_ww31/uefi/cht-m1stable/patches/cam-0439-atomisp2-css2401-and-2401_legacy-irci_master_2015070.patch
    ("atomisp2: css2401 and 2401_legacy-irci_master_20150701_0213")

Signed-off-by: Tsuchiya Yuto <kitakar@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>