Bluetooth: Remove unneeded macros

Remove the `bt_hex`, `bt_addr_str`, `bt_addr_le_str` and `bt_uuid_str`
macros from `bt_str.h` as they were just aliases for the `*_real` functions
in the same file.

The functions has been renamed without the `_real` suffix.

Some files were using the functions and not the macros, they have been
updated to use the new name of the functions.

Signed-off-by: Théo Battrel <theo.battrel@nordicsemi.no>