powerpc/crashdump: Fix issues with kexec and 36bit physical addr

Fix sizes of variables so correct values are exported via /proc.
Cast variable in comparison to avoid compiler error.

Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 5fb667a..d254132 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -128,9 +128,9 @@
 	if (!csize)
 		return 0;
 
-	csize = min(csize, PAGE_SIZE);
+	csize = min_t(size_t, csize, PAGE_SIZE);
 
-	if (pfn < max_pfn) {
+	if ((min_low_pfn < pfn) && (pfn < max_pfn)) {
 		vaddr = __va(pfn << PAGE_SHIFT);
 		csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 	} else {