tests: lib: cbprintf_fp: add filter for tests using newlib

As some tests are enabling CONFIG_NEWLIB_LIBC, we need to
filter out that tests in case of missing NEWLIB support
in toolchain.
It can be done with 'filter: TOOLCHAIN_HAS_NEWLIB == 1'
filter in testcase.yaml

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>