AA: ath9k: add workaround for AR9331 USB host controller hang with USB1.1 devices

Backport of r39212

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/branches/attitude_adjustment@39407 3c298f89-4303-0410-b956-a3cf2f4a3e73
AA: ar71xx: fix bad RX sensitivity on newer TL-WDR4300 boards

Backport of r39392.

On recent TL-WDR4300 boards the external LNAs of the 2.4GHz
interface are connected to GPIO lines. Because these GPIO
lines are disabled by default, the RX sensitivity of the
device is quite bad.

Setup the GPIOs of the external LNAs to fix the issue.

[Backport note: the 'ath79_wmac_set_ext_lna_gpio' function
is not available in AA, use the 'gpio_request_one' instead.]

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/branches/attitude_adjustment@39408 3c298f89-4303-0410-b956-a3cf2f4a3e73