staging: vt6655: Use GFP_KERNEL in kzalloc

Four kzalloc functions are called with GFP_ATOMIC.
But according to driver call graph, they are not in atomic context,
namely no spinlock is held nor in an interrupt handler.

All these "GFP_ATOMIC"s are unnecessary,
and replace with with "GFP_KERNEL"s.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>