[MIPS] Make support for weakly ordered LL/SC a config option.

None of weakly ordered processor supported in tree need this but it seems
like this could change ...

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/include/asm-mips/system.h b/include/asm-mips/system.h
index 7633916..eba2e3d 100644
--- a/include/asm-mips/system.h
+++ b/include/asm-mips/system.h
@@ -117,7 +117,7 @@
 		raw_local_irq_restore(flags);	/* implies memory barrier  */
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return retval;
 }
@@ -165,7 +165,7 @@
 		raw_local_irq_restore(flags);	/* implies memory barrier  */
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return retval;
 }
@@ -246,7 +246,7 @@
 		raw_local_irq_restore(flags);	/* implies memory barrier  */
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return retval;
 }
@@ -352,7 +352,7 @@
 		raw_local_irq_restore(flags);	/* implies memory barrier  */
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return retval;
 }