sparc: Kill custom io_remap_pfn_range().

[ Upstream commit 3e37fd31 ]

To handle the large physical addresses, just make a simple wrapper
around remap_pfn_range() like MIPS does.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>