Revert "uio: constify of_device_id array"

This reverts commit 4d8beff2.

It causes build warnings, and it's incorrect as we do write to this
structure.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>