.editorconfig: add .editorconfig file to help maintain coding style

Adds .editorconfig file to help maintain basic coding style
such as indent style and brackets across various IDEs. Editor
scans for this file and adheres to these rules.

Signed-off-by: Michal Lenc <michallenc@seznam.cz>

.editorconfig

@@ -0,0 +1,26 @@
+# EditorConfig: https://EditorConfig.org
+root = true
+
+[*]
+encoding = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{c,h}]
+indent_style = space
+indent_size = 2
+max_line_length = 78
+curly_bracket_next_line = true
+indent_brace_style = GNU
+
+[Makefile]
+indent_style = tab
+[Make.defs]
+indent_style = tab
+[Kconfig]
+indent_style = tab
+
+[*.sh]
+indent_style = tab
+max_line_length = 80