[docs][FileCheck] Fix invalid example

[thopre]

Summary

FileCheck documentation contains an example of a numeric variable
defined and used on the same line. This is not currently supported by
FileCheck so this commit fixes the example to use CHECK-SAME for the
variable use.

Test Plan: copy/pasted the example and tested with FileCheck without
this patch (failed) and with (succeeded).

[MaskRay]

LGTM. I remember you have a large patch series improving FileCheck. How many have landed now? If not all have landed, what is blocking the remaining changes?

[thopre]

In D79253#2015628, @MaskRay wrote:

LGTM. I remember you have a large patch series improving FileCheck. How many have landed now? If not all have landed, what is blocking the remaining changes?

9/12 of the patch series and plenty cleanup along the way. 11/12 is a tiny one and I'm not sure about 12/12 because it comes with potential pitfalls (allowing to use a variable defined on the same line). Nothing's blocking 10/12 except for the little amount of free time I have to progress on it but I'm actively working on it. Hopefully I can update the review (D60390) in 1-2 weeks time.

llvm/docs/CommandGuide/FileCheck.rst

* ``<expr>`` is an expression. An expression is in turn recursively defined
   before, after and between any of these elements.
 
 For example:
 
 .. code-block:: llvm
 
     ; CHECK: load r[[#REG:]], [r0]
     ; CHECK: load r[[#REG+1]], [r1]
-    ; CHECK: Loading from 0x[[#%x,ADDR:] to 0x[[#ADDR + 7]]
+    ; CHECK: Loading from 0x[[#%x,ADDR:]]
+    ; CHECK-SAME: to 0x[[#ADDR + 7]]
 
 The above example would match the text:
 
 .. code-block:: gas
 
     load r5, [r0]
     load r6, [r1]
     Loading from 0xa0463440 to 0xa0463447