spi: spi-msm-geni: Configure DFS index and clk before doing set rate

Currently we set rate before configure SPI DFS clk. Configure DFS
clk before doing set rate to SE clk. This will allow us to enable
correct parrent clk.

Change-Id: Ifa193bce28937ed363eadeb1bdc2e4bcbacb210b
Signed-off-by: Ashish Kori <akori@codeaurora.org>