ia64: remove now unused machvec indirections

ia64: remove now unused machvec indirections

With the SGI SN2 machvec removal most of the indirections are unused
now, so remove them.  This includes the entire removal of the mmio
read*/write* macros as the generic ones are identical to the
asm-generic/io.h version.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lkml.kernel.org/r/20190813072514.23299-17-hch@lst.de
Signed-off-by: Tony Luck <tony.luck@intel.com>