shim: compile time option to bypass the ExitBootServices() check

shim: compile time option to bypass the ExitBootServices() check

On systems where a second stage bootloader is not used, and the Linux
Kernel is booted directly from shim, shim's ExitBootServices() hook
can cause problems as the kernel never calls the shim's verification
protocol.  In this case calling the shim verification protocol is
unnecessary and redundant as shim has already verified the kernel
when shim loaded the kernel as the second stage loader.

This functionality is disabled by default and must be enabled via the
DISABLE_EBS_PROTECTION macro/define at build time.

Signed-off-by: Paul Moore <pmoore2@cisco.com>