arch/riscv/mcall.c: Return the correct memory base and size

Change-Id: Ibf471787ccb4f5393b0af737a9f7fc47b853a41a
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/17594
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
1 file changed