arch/riscv: Document mprv_{read,write}_* functions

Change-Id: Iaf0cb241f0eb4de241f0983c0b32dbcc28f96480
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/21342
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
1 file changed