btle_ll: Set advertising channel frequency
btle_ll: Set advertising channel frequency

Remove repeated deadline resets. Deadline reset now in the STANDBY state.
Set radio frequency to match selected channel.

TEST=ble_hci_adv 0
BUG=None
BRANCH=None

Change-Id: Ic7ff0dba862c0216301d138413a89e4ef4a812fe
Signed-off-by: Levi Oliver <a907be7b33793a1ae053f459aab8218dad738bec@google.com>
Reviewed-on: https://chromium-review.googlesource.com/367094
Reviewed-by: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec