RFR: 8355689: Wrong native entry name for FloatMaxVector vector math stubs with -XX:MaxVectorSize=8

[Vladimir Ivanov]

Both SVML and SLEEF libraries reuse 128-bit versions for vector of 2 floats. Usually, only `Float64Vector` shape satisfies that condiditon, but with`-XX:MaxVectorSize=8` `FloatMaxVector` becomes 2 element vector as well. 

Adjust the relevant logic to match vector of 2 floats shape structurally. 

Testing: failing regression test, hs-tier1 - hs-tier4

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/24936/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24936&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8355689
  Stats: 4 lines in 1 file changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/24936.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24936/head:pull/24936

PR: https://git.openjdk.org/jdk/pull/24936