staging: kpc2000: kpc_spi: remove unnecessary struct member chip_select

The structure kp_spi_controller_state, defined in the kpc2000_spi
driver, contains a member named chip_select which is never used after
initialization. Therefore, it should be removed for simplicity's sake.

Signed-off-by: Geordan Neukum <gneukum1@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>