[NVPTX] Fix failing tests on incompatible PTX version

Summary:
It seems some recent changes caused us to emit labels in the debug
sections. This is only allowed in PTX70 which caused the `ptxas` lines
to fail if present. Simply add `+ptx70` on it, maybe this needs to
investigate the change that caused this? But I'm not sure how much we
care about the older targets.

Author: jhuber6

llvm/test/DebugInfo/NVPTX/dbg-value-const-byref.ll

@@ -1,5 +1,5 @@
 ; RUN: llc -mtriple=nvptx64-nvidia-cuda < %s | FileCheck %s
-; RUN: %if ptxas %{ llc -mtriple=nvptx64-nvidia-cuda < %s | %ptxas-verify %}
+; RUN: %if ptxas %{ llc -mtriple=nvptx64-nvidia-cuda -mattr=+ptx70 < %s | %ptxas-verify %}
 
 ; Generated with -O1 from:
 ; int f1();

llvm/test/DebugInfo/NVPTX/debug-info.ll

@@ -1,5 +1,5 @@
 ; RUN: llc < %s -mtriple=nvptx64-nvidia-cuda | FileCheck %s
-; RUN: %if ptxas %{ llc < %s -mtriple=nvptx64-nvidia-cuda | %ptxas-verify %}
+; RUN: %if ptxas %{ llc < %s -mtriple=nvptx64-nvidia-cuda -mattr=+ptx70 | %ptxas-verify %}
 
 ; // Bitcode in this test case is reduced version of compiled code below:
 ;__device__ inline void res(float x, float y, ptr res) { *res = x + y; }

llvm/test/DebugInfo/NVPTX/debug-loc-offset.ll

@@ -1,5 +1,5 @@
 ; RUN: llc -mtriple=nvptx64-nvidia-cuda < %s | FileCheck %s
-; RUN: %if ptxas %{ llc -mtriple=nvptx64-nvidia-cuda < %s | %ptxas-verify %}
+; RUN: %if ptxas %{ llc -mtriple=nvptx64-nvidia-cuda < %s -mattr=+ptx70 | %ptxas-verify %}
 
 ; CHECK: .target sm_{{[0-9]+}}, debug