fix(plat/qemu): reboot/shutdown with low to high gpio
fix(plat/qemu): reboot/shutdown with low to high gpio

Use low to high gpio sequence to reboot/shutdown qemu machine.

Use low to high gpio pins level change which will cause an interrupt
in qemu virt platform. This change will supported with next qemu 6.1
release once patchset:
hw/arm: Make virt board secure powerdown/reset work
will be merged.

Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>
CC: Peter Maydell <313afa09ce093b19ae1dd74f57c1ebd94508584c@linaro.org>
Change-Id: I70979517358c3b587722b2dcb33f63d29bf79d9b

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware