[AArch64] Correctly mark Neoverse N2 as an Armv9.0a core (#75055)

Neoverse N2 was incorrectly marked as an Armv8.5a core. This has been
changed to an Armv9.0a core. However, crypto options are not enabled
by default for Armv9 cores, so -mcpu=neoverse-n2+crypto is required
to enable crypto for this core.

Neoverse N2 Technical Reference Manual:
   https://developer.arm.com/documentation/102099/0003/