Fixes the following build problem:
mips-linux-gnu-ld:arch/mips/kernel/vmlinux.lds:253: syntax error

because VMLINUX_LOAD_ADDRESS was an empty string for that platform
so the vmlinux.lds.S created an invalid section entry on line 50.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Acked-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: sibyte-users@bitmover.com
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5548/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>