drop obsolete sys_ioctl export

sys_ioctl() was only exported for our first version of compat ioctl
handling.  Now that the whole compat ioctl handling mess is more or less
sorted out there are no more modular users left and we can kill it.

There's one exception and that's sparc64's solaris compat module, but
sparc64 has it's own export predating the generic one by years for that
which this patch leaves untouched.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>