RFR: 8302328: [s390x] Simplify asm_assert definition [v4]

[Amit Kumar]

> This PR cleanups some assert statements and specifies branch condition at calling site itself. Remaining asm_assert methods are inlined as well.

Amit Kumar has updated the pull request incrementally with one additional commit since the last revision:

  address comment from Martin

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12822/files
  - new: https://git.openjdk.org/jdk/pull/12822/files/cbfe5172..5635d301

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12822&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12822&range=02-03

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/12822.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/12822/head:pull/12822

PR: https://git.openjdk.org/jdk/pull/12822