Zfinx/Zdinx are new extensions ratified in 2022, it similar to F/D extensions,
support hard float operation for single/double precision, but the difference
between Zfinx/Zdinx and F/D is Zfinx/Zdinx is operating under general purpose
registers rather than dedicated floating-point registers.
This patch improve the hard float support detection for RISC-V port, so
that Zfinx/Zdinx can have better/right performance.
Co-authored-by: Jesse Huang <jesse.huang@sifive.com>
d572c4482b