ld: Fix retain7a.d XFAIL/notarget entry for hppa

PR 30733
* ld/testsuite/ld-elf/retain7a.d: Fix XFAIL entry for hppa to match
  hppa{1.1,2.0}*, like hppa2.0-unknown-linux-gnu which Gentoo uses.

Signed-off-by: Sam James <sam@gentoo.org>