arm: dts: k3-binman: Make optee optional as requirement

Allow boards that use ti_spl_template to not use optee part in
configuration.
Vendor can have module with 256 Mb of memory and they try to optimize
the available memory just using the essential components.
This change allow to remove tee from configuration without binman
fail.

configurations {
	default = "conf-0";

	conf-0 {
		description = "k3-am62_ccm_m3";
		firmware = "atf";
		loadables = "dm", "spl";
		fdt = "fdt-0";
	};
};

Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>

arch/arm/dts/k3-binman.dtsi

@@ -293,6 +293,7 @@
 						keyfile = "custMpk.pem";
 					};
 					tee: tee-os {
+						optional;
 					};
 				};
 
@@ -360,6 +361,7 @@
 					entry = <0x9e800000>;
 					tee-os {
 						filename = "tee-raw.bin";
+						optional;
 					};
 				};