mesa: expose dimension check for glTex*Storage functions

mesa: expose dimension check for glTex*Storage functions

This is done so that following patch can use it to verify dimensions
for multisample variants of glTex*Storage.

v2: move function to header, use bool instead GLboolean
v3: small changes, cleanup

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Timothy Arceri <t_arceri@yahoo.com.au>