soc: qcom: pil: Clear elf region on authentication failure

In existing implementation elf region was being clearead before memory
access to firmware region assigned to HLOS. So to avoid it using
separate function which will be called only when HLOS is the owner.

Change-Id: I8bb22e4dbe3e1f898678d0c0f6e60268b88fc150
Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org>