ram: Rename qemu_target_page_bits() to qemu_target_page_size()

It was used as a size in all cases except one.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
diff --git a/exec.c b/exec.c
index c97ef4a..7a640c7 100644
--- a/exec.c
+++ b/exec.c
@@ -3307,9 +3307,9 @@
  * Allows code that needs to deal with migration bitmaps etc to still be built
  * target independent.
  */
-size_t qemu_target_page_bits(void)
+size_t qemu_target_page_size(void)
 {
-    return TARGET_PAGE_BITS;
+    return TARGET_PAGE_SIZE;
 }
 
 #endif