linux-imx

rw_verify_area(): saner calling conventions

Lift length capping into the few callers that care about it.  Most of
them treat all non-negatives as "success" and ignore the capped value,
and with good reasons.

Make rw_verify_area() return 0 on success.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>