Bluetooth: do not use assignment in if condition

Fix checkpatch errors like:
"ERROR: do not use assignment in if condition"
Simplify code and fix one long line.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@nokia.com>
Acked-by: Ville Tervo <ville.tervo@nokia.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>