staging: gpib: switch to kmalloc(sizeof(*status))

Fix checkpatch warning:

Prefer kmalloc(sizeof(*status)...) over
kmalloc(sizeof(struct gpib_status_byte)...)

Signed-off-by: Andreas Kleinbichler <andi.kleinbichler@gmail.com>
Link: https://lore.kernel.org/r/aCdY-OgvoTUjcIeF@andreas-VirtualBox


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>