ldrp_V2 : Core context extraction if kernel executing at EL2

These changes add a new option --kernel-exception-level
which can be passed from command line to specify the
current exception level of kernel. This is to handle
a case where backtrace should get generated if kernel
is executing at EL2 instead of EL1.

Change-Id: If0d61119a6cc27e263d73ce9921a63cab4bdee45
Signed-off-by: Kumar Harsh <harkumar@codeaurora.org>