reflect: add a floating point section to DeepEqual tests

The floating point tests were all added into the Inequalities section,
instead of separated into Equalities vs Inequalities.

Rather than separate them, add a new floating point section.

Change-Id: I3713a5aff5850dcc0caf68a754633d695a03ded9
Reviewed-on: https://go-review.googlesource.com/c/go/+/349612


Trust: Josh Bleecher Snyder <josharian@gmail.com>
Trust: Joe Tsai <joetsai@digital-static.net>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Joe Tsai <joetsai@digital-static.net>
Reviewed-by: Joe Tsai <joetsai@digital-static.net>
TryBot-Result: Go Bot <gobot@golang.org>