sm8x50-userdebug: Add a generic build target for Snapdragon 8 gen devboards

Supported only on Linux kernel v6.8 onwards, this is a
common configuration (64-bit only) target for Snapdragon 8
gen devboards.

Smoke tested on sm8550-hdk, sm8550-qrd and sm8650-qrd with
software rendering.

And since qcom,board-id and qcom,msm-id DT properties are no
longer accepted upstream, we used fdtoverlay to apply them
at build time. So make sure that the base DT is built with
`DTC_FLAGS=-@` build flag to allow overlays, otherwise
fdtoverlay command will run into "FDT_ERR_NOTFOUND" error at
the build time.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Change-Id: I2c6a0331173ef11a542b07ee3a270ece36d96786
diff --git a/sm8x50/dtb-overlays/sm8550-hdk.dts b/sm8x50/dtb-overlays/sm8550-hdk.dts
new file mode 100644
index 0000000..caf4dc1
--- /dev/null
+++ b/sm8x50/dtb-overlays/sm8550-hdk.dts
@@ -0,0 +1,7 @@
+/dts-v1/;
+/plugin/;
+
+&{/} {
+	qcom,msm-id = <536 0x10000>, <536 0x20000>, <601 0x20000>;
+	qcom,board-id = <0x1001f 0>;
+};