generic: platform/mikrotik: fix LZOR support

generic: platform/mikrotik: fix LZOR support

31e99fe3da which introduced this code was unfortunately untested.
This commit fixes a number of issues and works around the fact that in
this particular scheme, the LZO payload may be padded at the end which
will trigger a harmless lzo decompression error.
This commit also disambiguates the debug printks.

Tested-by: Robert Marko <robimarko@gmail.com>
Signed-off-by: Thibaut VARÈNE <hacks@slashdirt.org>
Fixes: 31e99fe3da ("generic: platform/mikrotik: support LZOR encoding")
(cherry picked from commit 2ea481193c1654c9cb42aa0331cdbc4570783e26)