i965: Add missing break in SHADER_OPCODE_GEN7_SCRATCH_READ case.

Fixes "Missing break in switch" defect reported by Coverity.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Cc: "10.0" <mesa-stable@lists.freedesktop.org>

src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp

@@ -335,6 +335,8 @@ schedule_node::set_latency_gen7(bool is_haswell)
        * then around 140.  Presumably this is cache hit vs miss.
        */
       latency = 50;
+      break;
+
    case SHADER_OPCODE_UNTYPED_ATOMIC:
       /* Test code:
        *   mov(8)    g112<1>ud       0x00000000ud       { align1 WE_all 1Q };