getauxval(AT_HWCAP) returns different value under qemu-system-riscv64 and qemu-riscv64
Description of problem:
I have a test program that checks for the presence of the RISC-V Vector extension (RVV) via getauxval().

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

#define ISA_V_HWCAP (1 << ('v' - 'a'))

void main() {
  unsigned long hw_cap = getauxval(AT_HWCAP);
  printf("RVV %s\n", hw_cap & ISA_V_HWCAP ? "detected" : "not found");
}
```

When run inside `qemu-system-riscv64` with a 6.5-rc3 kernel where `CONFIG_RISCV_ISA_V=y` and `CONFIG_RISCV_ISA_V_DEFAULT_ENABLE=y` it correctly shows:

```
$ ./hwcap
RVV detected
```

However when executed with `qemu-riscv64` it does not return the V bit set:

```
$ qemu-riscv64 hwcap
RVV not found
```
Steps to reproduce:
1. Boot 6.5-rc3 kernel with `CONFIG_RISCV_ISA_V=y` and `CONFIG_RISCV_ISA_V_DEFAULT_ENABLE=y`
2. In guest run test program hwcap (source above)
3. On host run `qemu-riscv64 hwcap`
Additional information: