MIPS: Add iomem resource for kernel bss section.

MIPS: Add iomem resource for kernel bss section.

The kexec/kdump tools need to know where the .bss is so it can be
included in the core dump.  This allows vmcore-dmesg to have access to
the dmesg buffers of the crashed kernel as well as allowing the
debugger to examine variables in the bss section.

Add a request for the bss resource in addition to the already
requested code and data sections.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Steven J. Hill <steven.hill@cavium.com>,
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17485/
Signed-off-by: James Hogan <jhogan@kernel.org>