.editorconfig: remove trim_trailing_whitespace option

Some editors (like the vim variants), when seeing "trim_whitespace"
decide to do just that for all of the whitespace in the file you are
saving, even if it is not on a line that you have modified.  This plays
havoc with diffs and is NOT something that should be intended.

As the "only trim whitespace on modified lines" is not part of the
editorconfig standard yet, just delete these lines from the
.editorconfig file so that we don't end up with diffs that are
automatically rejected by maintainers for containing things they
shouldn't.

Cc: Danny Lin <danny@kdrag0n.dev>
Cc: Íñigo Huguet <ihuguet@redhat.com>
Cc: Mickaël Salaün <mic@digikod.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Fixes: 5a602de9

 ("Add .editorconfig file for basic formatting")
Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/2024061137-jawless-dipped-e789@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>