logging: Use vprintk for string formatting by default

Previously, _prf function was used when present and _vprintk
was used otherwise. _prf supports reacher formatting but at
cost of 3k flash and >250 bytes on stack. Stack usage then
depended on which function was used and that was causing
troubles when trimming stack sizes.

Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
2 files changed