acpi: Use tprintf-based API for logging

Start using tprintf as in drivers/pci.cc, for example, and switch to
'error' severity to disable early boot ACPI messages.

Eventually, core/debug.cc needs to be more dynamically configured but
for now it's good enough to use a standardized API and make the output
silent by default.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
tests: Fix bytes_written overflow in bdev-write and fs-stress

bytes_written can overflow while testing on a fast device.

Reviewed-by: Tomasz Grabiec <tgrabiec@gmail.com>
Signed-off-by: Asias He <asias@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
tests: Print err when bio is not finished correctly in bdev-write

This is useful to notify us that something goes wrong.

Reviewed-by: Tomasz Grabiec <tgrabiec@gmail.com>
Signed-off-by: Asias He <asias@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>