[PPC64] pgtable.h and other header cleanups

[Paul Mackerras]

David Gibson writes:

> This patch started as simply removing a few never-used macros from
> asm-ppc64/pgtable.h, then kind of grew.  It now makes a bunch of
> cleanups to the ppc64 low-level header files (with corresponding
> changes to .c files where necessary) such as:
> 	- Abolishing never-used macros
> 	- Eliminating multiple #defines with the same purpose
> 	- Removing pointless macros (cases where just expanding the
> macro everywhere turns out clearer and more sensible)
> 	- Removing some cases where macros which could be defined in
> terms of each other weren't
> 	- Moving imalloc() related definitions from pgtable.h to their
> own header file (imalloc.h)
> 	- Re-arranging headers to group things more logically
> 	- Moving all VSID allocation related things to mmu.h, instead
> of being split between mmu.h and mmu_context.h
> 	- Removing some reserved space for flags from the PMD - we're
> not using it.
> 	- Fix some bugs which broke compile with STRICT_MM_TYPECHECKS.
> 
> Signed-off-by: David Gibson <dwg at au1.ibm.com>

Acked-by: Paul Mackerras <paulus at samba.org>