powerpc/xmon: Remove renaming #defines of scanhex() and skipbl()

We have two #defines that rename scanhex() and skipbl() to
xmon_scanhex() and xmon_skipbl() - but no one ever uses those
names.

So the only effect is to rename the actual symbols in the generated
code, and AFACIS there is no reason to do that, so drop them.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>