net: ipa: kill ipa_table_valid()

What ipa_table_valid() (and ipa_table_valid_one(), which it calls)
does is ensure that the memory regions that hold routing and filter
tables have reasonable size.  Specifically, it checks that the size
of a region is sufficient (or rather, exactly the right size) to
hold the maximum number of entries supported by the driver.  (There
is an additional check that's erroneous, but in practice it is never
reached.)

Recently ipa_table_mem_valid() was added, which is called by
ipa_table_init().  That function verifies that all table memory
regions are of sufficient size, and requires hashed tables to have
zero size if hashing is not supported.  It only ensures the filter
table is large enough to hold the number of endpoints that support
filtering, but that is adequate.

Therefore everything that ipa_table_valid() does is redundant, so
get rid of it.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>