spi: spi-geni-qcom: Set the Link Rx bit

Set the Link Rx field when there is any data expected on the Rx channel
as required by the Hardware programming guide.

Change-Id: Ia43ab480a315f592c25622c4b59779650a7bc5e4
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>