ARM: dts: msm: Fix SPI0 chip select definitions on 8974

In the process of updating SPI device tree definitions,
commit 9305cdd5 redefined
GPIO 9 as SPI CS0 instead of CS2, causing the KS8851 SPI
Ethernet controller (which is tied to SPI0 CS2) to stop
working.

Change-Id: I421c0b9a6fc00324acd5b1e939997a2af417c587
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>