aarch64: testsuite: disable PIE for aapcs64 tests [PR70150]

If GCC is built with --enable-default-pie, a lot of aapcs64 tests fail
because relocation unsupported in PIE is used.

gcc/testsuite/ChangeLog:

	PR testsuite/70150
	* gcc.target/aarch64/aapcs64/aapcs64.exp (additional_flags):
	Add -fno-pie -no-pie.