media: staging: atomisp: stop mixing enum types

This driver abuses on enum types:

    drivers/staging/media/atomisp/pci/atomisp2/atomisp_compat_css20.c:1027:37: warning: mixing different enum types
    drivers/staging/media/atomisp/pci/atomisp2/atomisp_compat_css20.c:1027:37:     int enum ia_css_csi2_port  versus
    drivers/staging/media/atomisp/pci/atomisp2/atomisp_compat_css20.c:1027:37:     int enum mipi_port_ID_t
    drivers/staging/media/atomisp/pci/atomisp2/atomisp_compat_css20.c:1037:39: warning: mixing different enum types
    drivers/staging/media/atomisp/pci/atomisp2/atomisp_compat_css20.c:1037:39:     int enum ia_css_csi2_port  versus
    drivers/staging/media/atomisp/pci/atomisp2/atomisp_compat_css20.c:1037:39:     int enum mipi_port_ID_t
    drivers/staging/media/atomisp/pci/atomisp2/atomisp_compat_css20.c:2147:62: warning: mixing different enum types
    drivers/staging/media/atomisp/pci/atomisp2/atomisp_compat_css20.c:2147:62:     int enum mipi_port_ID_t  versus
    drivers/staging/media/atomisp/pci/atomisp2/atomisp_compat_css20.c:2147:62:     int enum ia_css_csi2_port

Doing some "implicit" typecast. Fix it by using just one enum
everywhere, and stopping using typedef to refer to it.

Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>