esp.c: add asc_mode property to indicate the current ESP mode

esp.c: add asc_mode property to indicate the current ESP mode

Add a new asc_mode property to ESPState which indicates the current mode of
the ESP and update the ESP state machine accordingly.

Bump the vmstate version and include migration logic to ensure that asc_mode
is set to initiator mode such that any commands in progress will always
continue.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250711204636.542964-7-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>