arm64: uprobe: Return EOPNOTSUPP for AARCH32 instruction probing

As stated in linux/errno.h, ENOTSUPP should never be seen by user programs.
When we set up uprobe with 32-bit perf and arm64 kernel, we would see the
following vague error without useful hint.

The sys_perf_event_open() syscall returned with 524 (INTERNAL ERROR:
strerror_r(524, [buf], 128)=22)

Use EOPNOTSUPP instead to indicate such cases.

Signed-off-by: He Zhe <zhe.he@windriver.com>
Link: https://lore.kernel.org/r/20210223082535.48730-1-zhe.he@windriver.com


Cc: <stable@vger.kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>