hifive-unleashed: update documentation to match current state

Signed-off-by: Philipp Hug <philipp@hug.cx>
Change-Id: I3f1b7dd4ef52a64c9a222f2d5cffe2b73806fe4e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32182
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>

Documentation/mainboard/sifive/hifive-unleashed.md

@@ -12,15 +12,13 @@ For general setup instructions, please refer to the [Getting Started Guide].
 The following things are still missing from this coreboot port:
 
 - Support running romstage from flash (fix stack) to support boot mode 1
-- CBMEM support
-- FU540 clock configuration
-- FU540 RAM init
-- Placing the ramstage in DRAM
 - Starting the U54 cores
 - FU540 PIN configuration and GPIO access macros
 - Provide serial number to payload (e.g. in device tree)
+- Implement instruction emulation
 - Support for booting Linux on RISC-V
-
+- Add support to run OpenSBI payload in m-mode
+- SMP support in trap handler
 
 ## Configuration