In the non-avx case, we are incorrectly using DefineSameAsFirst, which
is wrong, since operand0 is a 32-bit register, but the output should be
a simd register. This error was caught by running the test with flag:
--no-enable-avx, leading to a register allocator verifier failure.

Drive by cleanup to remove duplicate cases for avx and see in i64x2 replace
lane.

Bug: v8:9728
Change-Id: I96490c82e13660fc41e72ac523e5be37b051b624
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1866963
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64363}