trezorctl: set homescreen for T2

trezorctl

@@ -209,7 +209,11 @@ def set_flags(connect, flags):
 @click.option('-f', '--filename', default=None)
 @click.pass_obj
 def set_homescreen(connect, filename):
-    if filename is not None:
+    if filename and filename.endswith('.toif'):
+        img = open(filename, 'rb').read()
+        if img[:8] != b'TOIf\x90\x00\x90\x00':
+            raise ValueError('File is not a TOIF file with size of 144x144')
+    elif filename is not None:
         from PIL import Image
         im = Image.open(filename)
         if im.size != (128, 64):