media: atomisp: csi_rx.c: add missing includes

Due to that, smatch warns with:

drivers/staging/media/atomisp/pci/css_2401_system/host/csi_rx.c:18:11: warning: symbol 'N_SHORT_PACKET_LUT_ENTRIES' was not declared. Should it be static?
drivers/staging/media/atomisp/pci/css_2401_system/host/csi_rx.c:24:11: warning: symbol 'N_LONG_PACKET_LUT_ENTRIES' was not declared. Should it be static?
drivers/staging/media/atomisp/pci/css_2401_system/host/csi_rx.c:30:11: warning: symbol 'N_CSI_RX_FE_CTRL_DLANES' was not declared. Should it be static?
drivers/staging/media/atomisp/pci/css_2401_system/host/csi_rx.c:37:11: warning: symbol 'N_CSI_RX_BE_SID_WIDTH' was not declared. Should it be static?
drivers/staging/media/atomisp/pci/css_2401_system/host/ibuf_ctrl.c:19:11: warning: symbol 'N_IBUF_CTRL_PROCS' was not declared. Should it be static?

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: atomisp: add SPDX headers

This driver is licensed under GPL 2.0, as stated inside their
headers.

Add the proper tag there. We should probably latter cleanup
the reduntant licensing text, but this could be done later,
after we get rid of other abstraction layers.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: atomisp: remove some file duplication and do more dir renames

There are currently two identical copies of some files, one
at css_2401_csi2p_system/ and another one at css_2401_system/.

Get rid of one of them, moving the remaining files to the
directory with the shortest name.

While here, do more renames, in order to get smaller path
names.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>