staging: unisys: visornic: Replace GFP_ATOMIC with GFP_KERNEL

As per below information

GFP_KERNEL  FLAG

This is a normal allocation and might block. This is the flag to use in
process context code when it is safe to sleep.

GFP_ATOMIC FLAG

The allocation is high-priority and does not sleep. This is the flag to
use in interrupt handlers, bottom halves and other situations where you
cannot sleep

And we can take advantage of GFP_KERNEL , as when system is in low
memory chances of getting success is high compared to GFP_ATOMIC.

As visornic_probe is in  process context we can use GPF_KERNEL.

Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>