RFR[XXS]: 8248682: AArch64: Use ATTRIBUTE_ALIGNED helper

[Ludovic Henry]

Hello,

Simple code cleanup to use existing ATTRIBUTE_ALIGNED macro in src/hotspot/cpu/aarch64.

JBS: https://bugs.openjdk.java.net/browse/JDK-8248682
Webrev: http://cr.openjdk.java.net/~burban/luhenry/8248682/webrev.00

Testing: jtreg:test/hotspot/jtreg:tier1, jtreg:test/jdk:tier1, jtreg:test/jdk:tier2, jtreg:test/langtools, on Windows-AArch64 and Linux-AArch64.

Thank you,

--
Ludovic