Recommit "[RISCV] Add separate lookup tables for fli.h and fli.d."

Fix mistake in f16 table in previous patch.

Original commit message:
Use separate lookup tables instead of trying to reuse the fli.s
table.

We were missing the 2 denormal cases for fli.h. We also had an issue
where fli.d was only checking 8 bits of the 11 bit exponent.