The current code treats the type of SIMD&FP register as C_REG incorrectly.

The fix code converts C_REG type into C_FREG type.

Uncomment fcsels/fcseld test cases.

Fixes #21582
Change-Id: I754c51f72a0418bd352cbc0f7740f14cc599c72d
Reviewed-on: https://go-review.googlesource.com/58350Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>