BLE bond information is stored in a table in flash memory during the pairing process with another BLE device.
This information is required for a secure BLE connection.
There is a limit to the number of entries in this table. It used to be 4 but was recently changed to 2
during a code merge with mbed updates. This patch returns to support four bonds.
The hash function is needed to generate this a new Private Resolvable address.
This functionality is required to generate a table with a list of addresses
from the information in the bond table (See the getAddressesFromBondTable() API
in BLE API SecurityManager). However, this function is not exposed by the
nRF51 SDK to external code. This pull requests simply adds the function
declaration to the relevant .h file to make external use possible.