ARM: dts: msm: update the clock frequency of SPI slave node to 24Mhz

Packets loss has been observed during WDSP SVA on SDM845. Resolving
this issue by increasing the clock frequency of SPI slave node to
improve the performance of WDSP SVA.

Change-Id: I6f8276a785acdbc5e55716390a8e8cfbeb56059a
Signed-off-by: Xiaoyu Ye <benyxy@codeaurora.org>