x86/mm/64: Rename the register_page_bootmem_memmap() 'size' parameter to 'nr_pages'

register_page_bootmem_memmap()'s 3rd 'size' parameter is named
in a somewhat misleading fashion - rename it to 'nr_pages' which
makes the units of it much clearer.

Meanwhile rename the existing local variable 'nr_pages' to
'nr_pmd_pages', a more expressive name, to avoid conflict with
new function parameter 'nr_pages'.

(Also clean up the unnecessary parentheses in which get_order() is called.)

Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: akpm@linux-foundation.org
Link: http://lkml.kernel.org/r/1509154238-23250-1-git-send-email-bhe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 065d99d..b2c7045 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2495,7 +2495,7 @@
 void vmemmap_free(unsigned long start, unsigned long end);
 #endif
 void register_page_bootmem_memmap(unsigned long section_nr, struct page *map,
-				  unsigned long size);
+				  unsigned long nr_pages);
 
 enum mf_flags {
 	MF_COUNT_INCREASED = 1 << 0,