staging: pi433: style fix - space after asterisk

This patch is intended to fix coding style issues in order to comply
with kernel coding style guide as requested by TODO file.

It fixes the following checkpatch.pl error:

ERROR: "foo * bar" should be "foo *bar"

Note:
"WARNING: line over 80 characters" remains valid here and could be fixed
by another patch.

Signed-off-by: Marcin Ciupak <marcin.s.ciupak@gmail.com>
Reviewed-by: Marcus Wolf <linux@wolf-entwicklungen.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>