staging: greybus: audio_topology: Fix spaces between operator and string

Fix coding style issue caught by checkpatch.pl related to the following
warning:
	- "CHECK: spaces preferred around that '*' (ctx:VxV) "

Signed-off-by: Emmanuil Chatzipetru <chatzi.emanuel@gmail.com>
Acked-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>