diag: Use correct bridge index while sending data

While sending data to remote processor pass the correct bridge
index value to the diag bridge driver. Rearrange init calls
so mempool values are initialized correctly.

CRs-Fixed: 997002
Change-Id: I524e48c38060865b6b83191202e5f057213abdca
Signed-off-by: Sreelakshmi Gownipalli <sgownipa@codeaurora.org>
Signed-off-by: Chris Lew <clew@codeaurora.org>