Bluetooth: has: Fix HAS features value

The bt_has_register_param's preset_sync_support and independent_presets
make sense only if CONFIG_BT_HAS_PRESET_COUNT is non-zero meaning the
CONFIG_BT_HAS_PRESET_SUPPORT is enabled.
Otherwise, those parameters shall be skipped.

Signed-off-by: Mariusz Skamra <mariusz.skamra@codecoup.pl>