Bluetooth: Setting security level based on remote device capabilities

Security level will be set to MEDIUM in case where the remote device
is 2.0 device. This would prevent it from going to 16 digit pairing
in case where the remote device sends the EIR and still doesn't
support SSP

CRs-fixed: 318469
Change-Id: I9d03b2b628cc188de44f44cfc3f8e81fbf3cb79d
Signed-off-by: Bhakthavatsala Raghavendra <braghave@codeaurora.org>