west: sign: remove -i 3 parameter

in some builds there is need to pass different value for -i parameter
and current code will override it to 3
Also in rimage i parameter is by default set to 3

Signed-off-by: Adrian Bonislawski <adrian.bonislawski@intel.com>

scripts/west_commands/sign.py

@@ -460,9 +460,9 @@ class RimageSigner(Signer):
             no_manifest = False
 
         if no_manifest:
-            extra_ri_args = ['-i', '3']
+            extra_ri_args = [ ]
         else:
-            extra_ri_args = ['-i', '3', '-e']
+            extra_ri_args = ['-e']
 
         sign_base = [tool_path]