MIPS: Remove unused variable 'lastpfn'

'lastpfn' is never used for anything. Remove it.

Signed-off-by: Steven J. Hill <steven.hill@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17276/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>