sparc64: Improvde documentation and readability of atomic backoff code.

Document what's going on in asm/backoff.h with a large and descriptive
comment.  Refer to it above the cpu_relax() definition in
asm/processor_64.h

Rename the pause patching section to have "3insn" in it's name like
the other patching sections do.

Based upon feedback from Sam Ravnborg.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/kernel/vmlinux.lds.S b/arch/sparc/kernel/vmlinux.lds.S
index 847f9f7..0bacceb 100644
--- a/arch/sparc/kernel/vmlinux.lds.S
+++ b/arch/sparc/kernel/vmlinux.lds.S
@@ -132,10 +132,10 @@
 		*(.popc_6insn_patch)
 		__popc_6insn_patch_end = .;
 	}
-	.pause_patch : {
-		__pause_patch = .;
-		*(.pause_patch)
-		__pause_patch_end = .;
+	.pause_3insn_patch : {
+		__pause_3insn_patch = .;
+		*(.pause_3insn_patch)
+		__pause_3insn_patch_end = .;
 	}
 	PERCPU_SECTION(SMP_CACHE_BYTES)