ath5k: remove dummy PCI "retry timeout" fix

Remove the PCI retry timeout code, for all the same reasons that
Luis Rodriguez removed it for ath9k.

Changes-licensed-under: 3-Clause-BSD

Cc: Luis Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>