Hexagon (target/hexagon) properly set FPINVF bit in sfcmp.uo and dfcmp.uo

Instead of checking for nan arguments, use float??_unordered_quiet

test cases added in a subsequent patch to more extensively test USR bits

Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20220210021556.9217-4-tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>