axp: Fix debugging support in DDR3 write leveling

If MV_DEBUG_WL is defined, DEBUG_WL_S and DEBUG_WL_D macros are missing.
In addition to that, get rid of debug output printing non-existent
counter variable.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Acked-by: Stefan Roese <sr@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>