msm: adsprpc: duplicate session info for shared context banks

Duplicate fastrpc session contexts for shared context banks
depending on the maximum number of sessions allowed.

Change-Id: I7028e70836e3ec32b789aefd0e9ef08dab87d881
Acked-by: Thyagarajan Venkatanarayanan <venkatan@qti.qualcomm.com>
Signed-off-by: Tharun Kumar Merugu <mtharu@codeaurora.org>