hostap: GFP_ATOMIC/GFP_KERNEL cleanup

The driver is allocating memory during initialization with GFP_ATOMIC
even though GFP_KERNEL is sufficient.  This patch fixes it.

Signed-off-by: Matt Renzelmann <mjr@cs.wisc.edu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>