adm80211: remove set but not used variables 'mem_addr' and 'io_addr'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/wireless/admtek/adm8211.c:1784:16:
 warning: variable mem_addr set but not used [-Wunused-but-set-variable]
drivers/net/wireless/admtek/adm8211.c:1785:15:
 warning: variable io_addr set but not used [-Wunused-but-set-variable]

They are never used, so can be removed.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>