spi: spi-msm-geni: Add spi slave mode support to QUPv3

Propagate SPI slave change from 4.14 to 5.4.
'commit db7d4f6203927b ("spi: spi-geni-qcom: Add spi
slave mode support to QUPv3")'.

Change-Id: I353198be51525572d8916ebbaab66db8e797c245
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>
Signed-off-by: Ashish Kori <akori@codeaurora.org>