[SveEmitter] Add builtins for svqadd, svqsub and svdot

This patch adds builtins for saturating add/sub instructions:
- svqadd, svqadd_n
- svqsub, svqsub_n

and builtins for dot product instructions:
- svdot, svdot_lane
diff --git a/clang/utils/TableGen/SveEmitter.cpp b/clang/utils/TableGen/SveEmitter.cpp
index 0638a21..d787e6e 100644
--- a/clang/utils/TableGen/SveEmitter.cpp
+++ b/clang/utils/TableGen/SveEmitter.cpp
@@ -532,6 +532,10 @@
     ElementBitwidth /= 2;
     NumVectors = 0;
     break;
+  case 'r':
+    ElementBitwidth /= 4;
+    NumVectors = 0;
+    break;
   case 'K':
     Signed = true;
     Float = false;