linux-firmware: Atheros ath9k is properly packaged in OE-Core

The firmware package has been done[1] during Daisy development cycle.

1. http://git.openembedded.org/openembedded-core/commit/meta/recipes-kernel/linux-firmware/linux-firmware_git.bb?h=daisy&id=0c9a853631ab423049817289bd660666a2c21222

So this bbappend is not required. This change removes the bbappend
and update the reach-image-qt4e to the new package which contains
the firmware.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>