[AArch64] Fix mapping testcase extra symbol from padding

After the backport of 799eafd ([AArch64] Don't tail-pads sections
to the alignment), gas will not emit superflous padding and thus
the extra '$x' special symbol is not emit anymore for mapping_{5,6}
tests.  This patch removes then on the expected output.

	* gas/testsuite/gas/aarch64/mapping_5.d: Remove extra symbol from
	superflous padding.
	* gas/testsuite/gas/aarch64/mapping_6.d: Likewise.

Change-Id: Id189010b4e6c89025d805eb2a02fa52ae20141ac
3 files changed