target/arm: Diagnose UNALLOCATED in disas_simd_two_reg_misc_fp16

target/arm: Diagnose UNALLOCATED in disas_simd_two_reg_misc_fp16

This fprintf+assert has been in place since the beginning.
It is prior to the fp_access_check, so we're still good to
raise sigill here.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/381
Signed-off-by: Richard Henderson <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-id: 20210604183506[email protected]
Reviewed-by: Peter Maydell <[email protected]>
Signed-off-by: Peter Maydell <[email protected]>