Bluetooth: Use lmp_sniffsubr_capable where applicable

This patch replaces all LMP_SNIFF_SUBR bit checking by the helper
macro lmp_sniffsubr_capable.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>