target-microblaze: mmu: Cleanup debug log messages

Cleanup debug log messages:
* Avoid long 80+ character lines.
* Remove D() macro and use qemu_log_mask.
* Remove logs that are not very useful

Suggested-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>