staging: wilc1000: Avoid GFP_KERNEL allocation from atomic context

txq_add_mgmt_pkt allocates memory while being called from atomic context
so needs to use GFP_ATOMIC

Signed-off-by: Adham Abozaeid <adham.abozaeid@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>