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

tools/testing/selftests/arm64/abi/syscall-abi.c

@@ -20,8 +20,6 @@
 
 #include "syscall-abi.h"
 
-#define NUM_VL ((SVE_VQ_MAX - SVE_VQ_MIN) + 1)
-
 static int default_sme_vl;
 
 static int sve_vl_count;