Coding guidelines 15.7 PR causes tests failures

[dcpleung]

The cbprintf_*.c changes in commit 163b7f0 causes test failures (as seen in https://buildkite.com/zephyr/zephyr/builds/28195). After reverting those changes, the failed test passed again.

1. tests/lib/mpsc_pbuf on qemu_riscv32: west build -d /tmp/build -p -b qemu_riscv32 tests/lib/mpsc_pbuf/ -t run

START - test_overwrite_consistency

    Assertion failed at WEST_TOPDIR/zephyr/tests/lib/mpsc_pbuf/src/main.c:855: validate_packet: ((uintptr_t)packet->hdr.data not equal to current_rd_idx)
Got 3911, expected: 3851
 FAIL - test_overwrite_consistency in 0.112 seconds

2. TFM integration test: west build -d /tmp/build -p -b mps2_an521_nonsecure samples/tfm_integration/tfm_psa_test/ -t run -- -DCONFIG_TFM_PSA_TEST_PROTECTED_STORAGE=y

************ Unknown Suite Report **********
TOTAL TESTS     : 39
TOTAL PASSED    : 5
TOTAL SIM ERROR : 0
TOTAL FAILED    : 17
TOTAL SKIPPED   : 17
******************************************

where all should pass.