staging: pi433: rf69.c style fix - spaces open brace

This patch fixes the following checkpatch.pl error:

ERROR: space required before the open brace '{'

in rf69.c file as requested by TODO file.

Signed-off-by: Marcin Ciupak <marcin.s.ciupak@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>