staging: greybus: authentication.c: Fix alignment should match open parenthesis

Fix the following error found by checkpatch.pl:
CHECK: Alignment should match open parenthesis
+static int cap_ioctl(struct gb_cap *cap, unsigned int cmd,
+			 void __user *buf)

Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>