staging: pi433: Fix ISO-8859 encoded non-english comments

Some comments, like "without memcpy would be nice", are removed.
Other comments are just translated to english.
rf69.c is now plain ASCII.

Signed-off-by: Simon Sandström <simon@nikanor.nu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>