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

This patch fixes the following checkpatch.pl error:

ERROR: that open brace { should be on the previous line

in rf69.c file as requested by TODO file.

Note:
ERROR: else should follow close brace '}'
remains valid here and is going to be fixed by the next patch in set.

Additionally some style warnings remain valid here and could be fixed by
another patch.

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