riscv-memlayout: fix existing memlayout issues, add sbi interface

Existing memlayout code placed sections in overlapping areas, and would
overwrite the payload if it was large enough. Update memlayout.ld in
src/mainboard/emulation/spike-riscv to represent the spike emulator, and
add sbi interface which now has room into src/arch/riscv/bootblock.S.
Add utility code to qemu-riscv, but emulator itself has yet to be
updated to new ISA and as such should not be used.
Update Makefile to include all the files necessary for sbi interface.

Clean up unused include in src/arch/riscv/include/atomic.h and
whitespace in src/mainboard/emulation/spike-riscv/memlayout.ld
Fixed whitespace issues in spike_util.c

Change-Id: Id97fe75e45ac1361005bec6d421756ee3f98a508
Signed-off-by: Thaminda Edirisooriya <thaminda@google.com>
Reviewed-on: http://review.coreboot.org/11370
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
7 files changed