power: reset: force warm_reset for thermal shutdown Also, remove shadow variable reboot_mode from exynos_reboot_mode_set. Bug: 232092738 Bug: 231628393 Change-Id: I2265e683c3a4b1003d1fea48c463eca3bedd9af9 Signed-off-by: Oleg Matcovschi <[email protected]> (cherry picked from commit 6f235f990267f424191b52bc7fd750732f9080d3)