mesa: add missing texture integer test in glTexSubImage()

mesa: add missing texture integer test in glTexSubImage()

If the texture format is integer, the incoming user data must also be
integer (and similarly for non-integer textures).

NOTE: This is a candidate for the stable branches.

Reviewed-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>