MIPS: Remove probe_tlb().

The function probe_tlb() only does anything for processors that are
not PRID_COMP_LEGACY.  This is precisely the set of processors for
which decode_configs() is called to do identical tlbsize probing
calculations.  Therefore probe_tlb() is completely redundant and may
be removed.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/865/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>