msm: secure_buffer: Add SPSS_HLOS_SHARED vmid

The SPSS_HLOS_SHARED vmid can be used along with SPSS VM
if an ION buffer is to be shared between SPSS and HLOS.

Change-Id: I14407343a924ab652b20ba5d93e72114473c7f8a
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
[lmark@codeaurora.org: don't include ION changes as these
 will be applied separately]
Signed-off-by: Liam Mark <lmark@codeaurora.org>