riscv: use mret to invoke M-mode payload and disable interrupts

Fixes a logic error that sets MPIE, but didn't use mret to return to the payload.
This left MIE set to an undefined value.

Now all modes are handled the same way:
- Trap vector base address point to the payload
- Disable Interrupt
- Return to payload using mret

TEST=Run an M-mode payload

Change-Id: Iaab595f916949c57104ec00f8b06ea047fe76bba
Signed-off-by: Xiang Wang <wxjstz@126.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33462
Reviewed-by: Philipp Hug <philipp@hug.cx>
Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

0 files changed, 0 insertions, 0 deletions