[POWERPC] Don't use 64k pages for ioremap on pSeries

On pSeries, the hypervisor doesn't let us map in the eHEA ethernet
adapter using 64k pages, and thus the ehea driver will fail if 64k
pages are configured.  This works around the problem by always
using 4k pages for ioremap on pSeries (but not on other platforms).
A better fix would be to check whether the partition could ever
have an eHEA adapter, and only force 4k pages if it could, but this
will do for 2.6.25.

This is based on an earlier patch by Tony Breeds.
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/mm/hash_utils_64.c

@@ -351,9 +351,14 @@ static void __init htab_init_page_sizes(void)
 		mmu_vmalloc_psize = MMU_PAGE_64K;
 		if (mmu_linear_psize == MMU_PAGE_4K)
 			mmu_linear_psize = MMU_PAGE_64K;
-		if (cpu_has_feature(CPU_FTR_CI_LARGE_PAGE))
+		if (cpu_has_feature(CPU_FTR_CI_LARGE_PAGE)) {
+			/*
+			 * Don't use 64k pages for ioremap on pSeries, since
+			 * that would stop us accessing the HEA ethernet.
+			 */
+			if (!machine_is(pseries))
 				mmu_io_psize = MMU_PAGE_64K;
-		else
+		} else
 			mmu_ci_restrictions = 1;
 	}
 #endif /* CONFIG_PPC_64K_PAGES */