ipw2x00: Remove unnecessary parentheses

Clang warns when multiple pairs of parentheses are used for a single
conditional statement.

drivers/net/wireless/intel/ipw2x00/ipw2200.c:5655:28: warning: equality
comparison with extraneous parentheses [-Wparentheses-equality]
                if ((priv->ieee->iw_mode == IW_MODE_ADHOC)) {
                     ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
drivers/net/wireless/intel/ipw2x00/ipw2200.c:5655:28: note: remove
extraneous parentheses around the comparison to silence this warning
                if ((priv->ieee->iw_mode == IW_MODE_ADHOC)) {
                    ~                    ^               ~
drivers/net/wireless/intel/ipw2x00/ipw2200.c:5655:28: note: use '=' to
turn this equality comparison into an assignment
                if ((priv->ieee->iw_mode == IW_MODE_ADHOC)) {
                                         ^~
                                         =
1 warning generated.

Link: https://github.com/ClangBuiltLinux/linux/issues/134


Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>