sm8750: Correct FastRPC to mailing list status

FastRPC seems to be never merged and status is only mailing list:
https://lore.kernel.org/all/?q=%22arm64%3A+dts%3A+qcom%3A+sm8750%3A+Add+adsp+fastrpc+nodes%2Fsupport%22

Signed-off-by: Krzysztof Kozlowski <[email protected]>

Author: krzk

_soc/sm8750.md

@@ -65,7 +65,7 @@ status-qfprom:
 status-remoteproc: 6.16
 status-remoteproc-adsp: 6.16
 status-remoteproc-cdsp: 6.16
-status-remoteproc-fastrpc: next-6.16
+status-remoteproc-fastrpc: mailing list
 status-remoteproc-mdsp: 6.16
 status-remoteproc-sdsp: N/A
 status-smmu: 6.14