soc: qcom: peripheral-loader: zero initialize pil imem region

Zero initialize the pil imem region so that clients that rely on
info in the imem region can determine the number of valid records
present in the region. Also move pil_image_info to the header so
its accessible to the clients.

Change-Id: I0e4d8c9176ac3b2977664005e41259df490b3967
Signed-off-by: Pratik Patel <pratikp@codeaurora.org>