intel: Remove num_mapped_regions assertion from _intel_batchbuffer_flush

There are cases where a buffer can be mapped while another buffer is
flushed.  This can happen in the CopyPixels meta-op path for piglit's
fbo-mipmap-copypix.  After some discussion with Eric, it seems this
assertion is no longer necessary, and it has always been too strict.

NOTE: This is a candidate for the 8.0 branch.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=43328
Cc: Eric Anholt <eric@anholt.net>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>

src/mesa/drivers/dri/intel/intel_batchbuffer.c

@@ -208,13 +208,6 @@ _intel_batchbuffer_flush(struct intel_context *intel,
 {
    int ret;
 
-   /* No batch should be emitted that uses a mapped region, because that would
-    * cause the map to be incoherent with GPU rendering done by the
-    * batchbuffer. To ensure that condition, we assert a condition that is
-    * stronger but easier to implement: that *no* region is mapped.
-    */
-   assert(intel->num_mapped_regions == 0);
-
    if (intel->batch.used == 0)
       return 0;