wireless: zd1211rw: remove redundant assignment of pointer 'q'

Pointer q is initialized and then almost immediately afterwards being
re-assigned the same value. Remove the second redundant assignment.

Cleans up clang warning:
drivers/net/wireless/zydas/zd1211rw/zd_mac.c:503:23: warning: Value
stored to 'q' during its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>