[NVPTX] Change begin/end inline asm comments to "begin/end inline asm".

Previously it was just "// inline asm", which made it tricky to read
code with lots of inline assembly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268994 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed