ARCMWDT: Fix cbprintf issue with omitted function prototype

MWDT requires function to be declared with argument types.
This PR provides explisitly type cast for out routine
inside z_cbvprintf_impl().

This PR also actual to LLVM-based compilers with strict
rules of compilation. It covers warnings generated with
additional flag -Wincompatible-function-pointer-types-strict.

This fixes https://github.com/zephyrproject-rtos/zephyr/issues/74562



Signed-off-by: Nikolay Agishev <agishev@synopsys.com>