haven: Fix buffer calculations for MEM_SHARE and MEM_LEND

The logic for calculating the request buffer sizes for the
MEM_SHARE and MEM_LEND resource manager calls is not present,
so add it.

Change-Id: I804ee108565733b0e4b376b5fd31abdb3d359c1f
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>