kselftest/arm64: Fix spelling misakes of signal names

There are a couple of spelling mistakes of signame names. Fix them.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20220907170902.687340-1-colin.i.king@gmail.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>