intel/isl/gen7: Allow msaa with 128-bit formats

intel/isl/gen7: Allow msaa with 128-bit formats

These formats are already allowed by the i965 GL driver, and the
feature seems to work just fine.

There are tests for multisampled rendering in piglit:
tests/spec/ext_framebuffer_multisample which can be patched to
try GL_RGBA16F/32F/16I/16UI/32I/32UI in addition to GL_RGBA/8I.
IvyBridge passed all tests with all sample numbers and even
with 128-bit formats.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Topi Pohjolainen <topi.pohjolainen@intel.com>