mb/google/brox: Sending End of Post (EOP) asynchronously
Currently EOP message is sent to CSE late in the boot flow. Instead send
it asynchronously to save ~10 ms in boot time.
BUG=b:
337330958
TEST=Build Brox BIOS Image and boot to OS.
Change-Id: I229d16a5dcd072958db3f59a9c364bf7508b3047
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82236
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Dinesh Gehlot <digehlot@google.com>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Eric Lai <ericllai@google.com>