convert remap_page_range() to remap_pfn_range() in a patch series shorter than 76 patches

Resolve physical address overflow issue in the remap_page_range() API by replacing it with remap_pfn_range(), which accepts its physical address argument as a pfn, hence allowing the use of a single-precision physical address argument without the risk of overflow at the API boundary. The above issue has hobbled support for various 32-bit architectures, including some embedded systems (ppc440 IIRC), caused persistent portability issues for sound drivers for legacy systems (sparc32; unfortunately this patch alone does not fully resolve those), and according to John Fusco's reports, made drivers for some PCI-X hardware infeasible to port to recent ia32 PAE enterprise systems. With this patch series applied, physical address overflows on 32-bit systems caused directly by remap_page_range() are gone forever, and ca. 100LOC of cut-and-waste driver code are swept out of existence alongside them.

-- wli

P.S.: The existing solution to the sparc32 issue was to pass a double
precision representation of the physical address as 2 single- precision arguments in an API (io_remap_page_range()) whose argument corresponding to those two was a single single- precision argument on most/all other architectures. The sparc32-specific issue requires more work beyond these patches to rectify. The most apparent consequence of the API skew is that drivers don't compile on sparc32 when they use io_remap_page_range() due to passing insufficient arguments, or vice-versa for drivers originally written for sparc32.