Bluetooth: hci_bcm: Clean up unnecessary #ifdef

pm_runtime_disable() and pm_runtime_set_suspended() are replaced with
empty inlines if CONFIG_PM is disabled, so there's no need to #ifdef
them.

device_init_wakeup() is likewise replaced with an inline, though it's
not empty, but it and devm_free_irq() can be made conditional on
IS_ENABLED(CONFIG_PM), which is preferable to #ifdef as per section 20
of Documentation/process/coding-style.rst.

Cc: Frédéric Danis <frederic.danis.oss@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>