The name of the HW_BEACON_OFFSET macro is a
bit confusing. It returns with one of the
HW_BEACON_BASE* values, so rename the macro
to HW_BEACON_BASE to reflect that.

The patch contains no functional changes.
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>