aux_util: fix missing format specifier #222

Job	Run time
scanbuild	6m 43s
coverity-test	0s
build-test (ubuntu-20.04, gcc)	4m 42s
test-coverage	4m 57s
test-fuzz	2m 32s
build-test (ubuntu-20.04, clang)	4m 24s
test-mbedtls (ubuntu-20.04)	2m 52s
build-test (fedora-32, gcc)	4m 36s
test-mbedtls (ubuntu-22.04-mbedtls-3.1)	2m 39s
test-no-crypto-build	1m 30s
build-test (fedora-32, clang)	5m 11s
test-tcti-config	14m 9s
build-test (opensuse-leap, gcc)	4m 31s
build-test (opensuse-leap, clang)	4m 35s
build-test (ubuntu-22.04, gcc)	4m 38s
build-test (ubuntu-22.04, clang)	4m 36s
build-test (alpine-3.15, gcc)	3m 56s
build-test (alpine-3.15, clang)	4m 42s
	1h 21m 13s

Provide feedback