amend "ath9k: Allow platform override without EEPROM override"

Originally Helmut posted a v2 of the "ath9k: Allow platform override
without EEPROM override", but I had prematurely commited the original
as commit 552a5157.  This commit restores the tree to what Helmut
intended with his v2 submission. -- JWL

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>