Bluetooth: Track feature pages in a single table

The local and remote features are organized by page number. Page 0
are the LMP features, page 1 the host features, and any pages beyond 1
features that future core specification versions may define. So far
we've only had the first two pages and two separate variables has been
convenient enough, however with the introduction of Core Specification
Addendum 4 there are features defined on page 2.

Instead of requiring the addition of a new variable each time a new page
number is defined, this patch refactors the code to use a single table
for the features. The patch needs to update both the hci_dev and
hci_conn structures since there are macros that depend on the features
being represented in the same way in both of them.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>