.editorconfig: hard tabs are still 8 spaces

The hard tab character is 8 spaces, that's just how it is.

Signed-off-by: H. Peter Anvin <[email protected]>

.editorconfig

@@ -8,4 +8,4 @@ insert_final_newline = true
 [{*.c,*.h}]
 indent_style = space
 indent_size = 4
-tab_width = 4
+tab_width = 8