devtool: drop unused plugin_init() functions

This function is no longer required to be defined for a plugin, so drop
it where it's a no-op.

(From OE-Core rev: 49716a5e27e704598321bd6c82275b16afc444aa)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/devtool/sdk.py

@@ -11,10 +11,6 @@ from devtool import exec_build_env_command, setup_tinfoil, DevtoolError
 
 logger = logging.getLogger('devtool')
 
-def plugin_init(pluginlist):
-    """Plugin initialization"""
-    pass
-
 def parse_locked_sigs(sigfile_path):
     """Return <pn:task>:<hash> dictionary"""
     sig_dict = {}