Hexagon (tests/tcg/hexagon) add floating point instructions to usr.c

Tests to confirm floating point instructions are properly
setting exception bits in USR

Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20220210021556.9217-8-tsimpson@quicinc.com>
Acked-by: Richard Henderson <richard.henderson@linaro.org>