kselftest/arm64: Fix .pushsection for strings in FP tests

The .pushsection directive used to store the strings used with the .puts
macro in the floating point helpers does not provide a section type but
according to the gas documentation this should be mandatory and with the
clang built in as it actually is. Provide one so that we can build these
tests with LLVM=1.

No functional change.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20230111-arm64-kselftest-clang-v1-1-89c69d377727@kernel.org


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