[MIPS] Ignore vmlinux.lds generated files
This patch adds the proper .gitignore file to ignore vmlinux.lds generated
in arch/mips/kernel/.
Signed-off-by: Florian Fainelli <florian.fainelli@telecomint.eu>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>