arm: mach-k3: Move TI dummy keys out of board folder

This file is used to emulate customer keys on TI development board
ecosystems, move it out of board/ directory and into mach-k3. And
change the relative paths to absolute paths in the binman paths.

While at it, drop the reference in verdin-binman file which is
redundant.

Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Acked-by: Manorit Chawdhry <m-chawdhry@ti.com>

arch/arm/dts/k3-am625-verdin-wifi-dev-binman.dtsi

@@ -5,10 +5,6 @@
 
 #include "k3-binman.dtsi"
 
-&custmpk_pem {
-	filename = "../../ti/keys/custMpk.pem";
-};
-
 #ifndef CONFIG_ARM64
 
 &bcfg_yaml {

arch/arm/dts/k3-binman.dtsi

@@ -13,7 +13,7 @@
 	custMpk {
 		filename = "custMpk.pem";
 		custmpk_pem: blob-ext {
-			filename = "../keys/custMpk.pem";
+			filename = "arch/arm/mach-k3/keys/custMpk.pem";
 		};
 	};