[ARM] nommu: adjust headers for !MMU ARM systems

Majorily based on Hyok Choi's patches, this fixes up the asm-arm
header files for mmuless systems.  Over and above Hyok's patches:

- nommu.h merged into mmu.h (it's only a structure)
- nommu_context.h is essentially the same as mmu_context.h, but
  without the MM switching code.

so there's no point having separate files.  Also, in memory.h,
there's no point #ifndef'ing PHYS_OFFSET and END_MEM - both
CONFIG_DRAM_BASE and CONFIG_DRAM_SIZE will always be set by the
configuration scripts.

Other files have minor formatting changes, but are essentially
the same.  Hyok's original patches were signed off thusly:

  Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

include/asm-arm/pgalloc.h

@@ -16,6 +16,10 @@
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 
+#define check_pgt_cache()		do { } while (0)
+
+#ifdef CONFIG_MMU
+
 #define _PAGE_USER_TABLE	(PMD_TYPE_TABLE | PMD_BIT4 | PMD_DOMAIN(DOMAIN_USER))
 #define _PAGE_KERNEL_TABLE	(PMD_TYPE_TABLE | PMD_BIT4 | PMD_DOMAIN(DOMAIN_KERNEL))
 
@@ -32,8 +36,6 @@ extern void free_pgd_slow(pgd_t *pgd);
 #define pgd_alloc(mm)			get_pgd_slow(mm)
 #define pgd_free(pgd)			free_pgd_slow(pgd)
 
-#define check_pgt_cache()		do { } while (0)
-
 /*
  * Allocate one PTE table.
  *
@@ -126,4 +128,6 @@ pmd_populate(struct mm_struct *mm, pmd_t *pmdp, struct page *ptep)
 	__pmd_populate(pmdp, page_to_pfn(ptep) << PAGE_SHIFT | _PAGE_USER_TABLE);
 }
 
+#endif /* CONFIG_MMU */
+
 #endif