bfa: allocate memory with GFP_ATOMIC in spinlock context

bfa_fcb_pbc_vport_create() is called only from bfa_fcs_pbc_vport_init(),
that is called only from bfad_drv_start() with bfad_lock spinlock held.
So the patch replaces GFP_KERNEL with GFP_ATOMIC to avoid
sleeping in atomic spinlock context.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Anil Gurumurthy <anil.gurumurthy@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>