diag: Set new context for peripheral error response

The patch sets new error context with TYPE_CMD for buf_num
context to add peripheral error responses on apps response
path to respective logging session and prevent buffer corruption.

Change-Id: I02c246d9a68a4f8e912d8693b3e4844c0e0b6885
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>