Disabling SVE via `-cpu max,sve=off` leaves SVE2 advertised by `getauxval`
Description of problem:
The documentation on https://qemu-project.gitlab.io/qemu/system/arm/cpu-features.html suggests that it should be possible to disable SVE support by passing `-cpu max,sve=off` on the command line, however this appears to only disable the SVE support advertised in the return value from `getauxval(AT_HWCAP)`. In particular it leaves SVE2 reported as enabled. This leaves the feature set advertised by `getauxval` in an inconsistent state since SVE is mandatory if SVE2 is available.

This may also affect other feature dependencies for example FEAT_SVE_BITPerm also requiring SVE2 to be available, I've not checked exhaustively.

For example, given the following code:

    #include <sys/auxv.h>
    #include <stdio.h>

    int main() {
      unsigned long hwcap = getauxval(AT_HWCAP);
      unsigned long hwcap2 = getauxval(AT_HWCAP2);

      if (hwcap & HWCAP_SVE) {
        printf("have sve!\n");
      } else {
        printf("don't have sve!\n");
      }
      if (hwcap2 & HWCAP2_SVE2) {
        printf("have sve2!\n");
      } else {
        printf("don't have sve2!\n");
      }
    }

We can observe the following:

    $ aarch64-linux-gnu-gcc test.c -static
    $ ../qemu-aarch64 -cpu max ./a.out
    have sve!
    have sve2!
    $ ../qemu-aarch64 -cpu max,sve=off ./a.out
    don't have sve!
    have sve2!

I don't believe that there is a `-cpu ...,sve2=off` option, so I would expect that disabling SVE also prevents SVE2 from being advertised as available.