Since the commit af7a06bac7:
`casa [..](10), .., ..` (and probably others alternate space instructions)
triggers a data access exception when the MMU is disabled.
When we enter get_asi(...) dc->mem_idx is set to MMU_PHYS_IDX when the MMU
is disabled. Just keep mem_idx unchanged in this case so we passthrough the
MMU when it is disabled.
Signed-off-by: KONRAD Frederic <frederic.konrad@adacore.com>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>