usx2y: don't bother with access_ok() in ->dsp_load()

usx2y: don't bother with access_ok() in ->dsp_load()

memdup_user() checks it, so the only effect would be failing with
-EINVAL instead of -EFAULT in case when access_ok() is false.
However, the caller has already checked access_ok() itself (and
would have buggered off with -EFAULT), so the check is completely
pointless.  Removing it both simplifies the only instance
of ->dsp_load() and allows to get rid of the check in caller -
its sole effect used to be in preventing a bogus error value
from access_ok() in the instance.  Let memdup_user() do the
right thing instead...

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