ath6kl: change name of sdio driver to ath6kl

Currently the name of the driver in struct sdio_driver is "ath6kl_sdio",
this is for example what uevent advertises. This is wrong as the module
is named as ath6kl.ko. Change it to "ath6kl" so that the names match.

Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>