diag: Cleanup client information on deinit Ioctl

Clean up the client pid information from the client table on
lsm_deinit Ioctl call. Also mutex protect the deinitialization
steps for any diag client.

Change-Id: I13410b0b1382de7b026726a3736f397dee1092fa
Signed-off-by: Sreelakshmi Gownipalli <sgownipa@codeaurora.org>
Signed-off-by: Katish Paran <kparan@codeaurora.org>