xen/arm64: io: Handle data abort due to cache maintenance instructions

xen/arm64: io: Handle data abort due to cache maintenance instructions

When the data abort is caused due to cache maintenance for an address,
there are three scenarios:-

1. Address belonging to a non emulated region - For this, Xen should
set the corresponding bit in the translation table entry to valid and
return to the guest to retry the instruction. This can happen sometimes
as Xen need to set the translation table entry to invalid. (for eg
'Break-Before-Make' sequence). Xen returns to the guest to retry the
instruction.

2. Address belongs to an emulated region - Xen should ignore the
instruction (ie increment the PC) and return to the guest.

3. Address is invalid - Xen should forward the data abort to the guest.

Signed-off-by: Ayan Kumar Halder <ayankuma@xilinx.com>
[julien: Don't initialize p.size to 1 << info->dabt.size]
Reviewed-by: Julien Grall <jgrall@amazon.com>