dtc: Allow overlays to have .dtbo extension

Allow the overlays to have .dtbo extension instead of just .dtb. This
allows them to be identified easily by tools as well as humans.

Allow the dtbo outform in dtc.c for the same.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Message-Id: <30fd0e5f2156665c713cf191c5fea9a5548360c0.1609926856.git.viresh.kumar@linaro.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

dtc.c

@@ -122,6 +122,8 @@ static const char *guess_type_by_name(const char *fname, const char *fallback)
 		return "dts";
 	if (!strcasecmp(s, ".yaml"))
 		return "yaml";
+	if (!strcasecmp(s, ".dtbo"))
+		return "dtb";
 	if (!strcasecmp(s, ".dtb"))
 		return "dtb";
 	return fallback;
@@ -357,6 +359,8 @@ int main(int argc, char *argv[])
 #endif
 	} else if (streq(outform, "dtb")) {
 		dt_to_blob(outf, dti, outversion);
+	} else if (streq(outform, "dtbo")) {
+		dt_to_blob(outf, dti, outversion);
 	} else if (streq(outform, "asm")) {
 		dt_to_asm(outf, dti, outversion);
 	} else if (streq(outform, "null")) {