bluetooth: macroize two small inlines to avoid module.h

These two small inlines make calls to try_module_get() and
module_put() which would force us to keep module.h present
within yet another common include header.  We can avoid this
by turning them into macros.  The hci_dev_hold construct
is patterned off of raw_spin_trylock_irqsave() in spinlock.h

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>