linux-user: Add missing TARGET_EDQUOT error code for Mips

EDQUOT is defined for Mips platform in Linux kernel in such a way
that it has different value than on most other platforms. However,
correspondent TARGET_EDQUOT for Mips is missing in Qemu code. Moreover,
TARGET_EDQUOT is missing from the table for conversion of error codes
from host to target. This patch fixes these problems.

Without this patch, syscalls add_key(), keyctl(), link(), mkdir(), mknod(),
open(), rename(), request_key(), setxattr(), symlink(), and write() will not
be able to return the right error code in some scenarios on Mips platform.
(Some of these syscalls are not yet supported in Qemu, but once they are
supported, they will need correct EDQUOT handling.)

Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Acked-by: Riku Voipio <riku.voipio@linaro.org>
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>