Fix initial implementation of min/max f32 instructions.

Bug: v8:6600
Change-Id: Icb30515b692caef2c33bd85f468e83c17cdef2a3
Reviewed-on: https://chromium-review.googlesource.com/1030493Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Commit-Queue: Sreten Kovacevic <sreten.kovacevic@mips.com>
Cr-Commit-Position: refs/heads/master@{#52836}