ath9k: fix misleading indentation

A cleanup patch in linux-3.18 moved around some code in the ath9k
driver and left some code to be indented in a misleading way,
made worse by the addition of some new code for p2p mode, as
discovered by a new gcc-6 warning:

drivers/net/wireless/ath/ath9k/init.c: In function 'ath9k_set_hw_capab':
drivers/net/wireless/ath/ath9k/init.c:851:4: warning: statement is indented as if it were guarded by... [-Wmisleading-indentation]
    hw->wiphy->iface_combinations = if_comb;
    ^~
drivers/net/wireless/ath/ath9k/init.c:847:3: note: ...this 'if' clause, but it is not
   if (ath9k_is_chanctx_enabled())
   ^~

The code is in fact correct, but the indentation is not, so I'm
reformatting it as it should have been after the original cleanup.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 499afacc ("ath9k: Isolate ath9k_use_chanctx module parameter")
Fixes: eb61f9f6 ("ath9k: advertise p2p dev support when chanctx")
Signed-off-by: David S. Miller <davem@davemloft.net>