kselftest/arm64: Remove the local NUM_VL definition

It was introduced in commit b77e995e ("kselftest/arm64: Add a test
program to exercise the syscall ABI") but never actually used. Remove it.

Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221218092942.1940-1-yuzenghui@huawei.com


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