Bluetooth: Fix eir name length

According to Section 1.2 of Core Specification Supplement Part A the
complete or short name strings are defined as utf8s, which should not
include the trailing NULL for variable length array as defined in Core
Specification Vol1 Part E Section 2.9.3.

Removing the trailing NULL allows PTS to retrieve the random address based
on device name, e.g. for SM/PER/KDU/BV-02-C, SM/PER/KDU/BV-08-C or
GAP/BROB/BCST/BV-03-C.

Fixes: f61851f6

 ("Bluetooth: Fix append max 11 bytes of name to scan rsp data")
Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>