staging: comedi: jr3_pci: rename data to sensor

Rename the `channel[x].data` member of `struct jr3_t` to
`channel[x].sensor` to match its type `struct jr3_sensor`.  Also rename
local variable `ch0data` in `jr3_pci_show_copyright()` to `sensor0` for
consistency.  It points to the `struct jr3_sensor` embedded in the
registers for "channel" 0.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>