Revert "uio: use request_threaded_irq instead"

Revert "uio: use request_threaded_irq instead"

BugLink: https://bugs.launchpad.net/bugs/1843487
Since mutex lock in irq hanler is useless currently, here will
remove it together with it.

This reverts commit 9421e45f5ff3d558cf8b75a8cc0824530caf3453.

Reported-by: james.r.harris@intel.com
CC: Ahsan Atta <ahsan.atta@intel.com>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(backported from commit 3d27c4de8d4fb2d4099ff324671792aa2578c6f9)
[kamal: applied just the mutex removal bit.]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>