gcc-6 warns about code in il3945_hw_txq_ctx_free() being
somewhat ambiguous:

drivers/net/wireless/intel/iwlegacy/3945.c:1022:5: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]

This adds a set of curly braces to avoid the warning.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NStanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>