ath9k: fix processing RXORN interrupts

The "goto chip_reset" is a bit misleading, because it does not actually
issue a chip reset. Instead it is bypassing processing of other
interrupts and assumes that the tasklet will issue a chip reset.

In the case of RXORN this does not happen, so bypassing processing of
other interrupts will simply allow them to fire again. Even if RXORN
was triggering a reset, it is not critical enough to need the bypass
here.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>