kselftest/arm64: Fix output formatting for za-fork

The za-fork test does not output a newline when reporting the result of
the one test it runs, causing the counts printed by kselftest to be
included in the test name.  Add the newline.

Fixes: 266679ff ("kselftest/arm64: Convert za-fork to use kselftest.h")
Cc: <stable@vger.kernel.org> # 6.4.x
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20231116-arm64-fix-za-fork-output-v1-1-42c03d4f5759@kernel.org


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>