RFR: 8292564: x86: Remove redundant casts in Assembler usages

[Aleksey Shipilev]

On Wed, 17 Aug 2022 19:29:18 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> Some of the casts are turned into `static_cast`s to assert that constants are small enough to fit into 32-bit immediate.

This confuses me a bit: I thought narrowing (implicit) conversions with `static_cast` would not assert safety in these cases. We have `checked_cast` for these.

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PR: https://git.openjdk.org/jdk/pull/9909