mesa/es: Remove redundant texture target validation

mesa/es: Remove redundant texture target validation

Mesa doesn't check the parameter passed to glMultiTexCoord*.  It does,
however, mask the texture value to prevent out-of-bounds writes.  This
patch will promote this non-conformant behavior to OpenGL ES 1.  I don't
think anyone will care, and the gets some silly code out of a hot path.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Brian Paul <brianp@vmware.com>