serial: ifx6x60: probe routine needs to call spi_setup

The probe routine should call spi_setup() to configure
the SPI bus so it can properly communicate with the device.
E.g. the device operates in SPI mode 1.

Called spi_setup to configure SPI mode, max_speed_hz, and bpw

Signed-off-by: Russ Gorby <russ.gorby@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>