s390: char: make slp_ctl explicitly non-modular

The Makefile currently controlling compilation of this code is obj-y,
meaning that it currently is not being built as a module by anyone.

Lets remove the couple traces of modular usage, so that when reading
the driver there is no doubt it is builtin-only.

Since module_misc_device translates to device_initcall in the non-modular
case, the init ordering remains unchanged with this commit.

Cc: Heiko Carstens <[e-mail]>
Cc: Paul Gortmaker <[e-mail]>
Cc: Michael Holzheu <[e-mail]>
Cc: [e-mail]
Signed-off-by: Paul Gortmaker <[e-mail]>
Acked-by: Martin Schwidefsky <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/s390/char/sclp_ctl.c

···
 #include <linux/uaccess.h>
 #include <linux/miscdevice.h>
 #include <linux/gfp.h>
-#include <linux/module.h>
+#include <linux/init.h>
 #include <linux/ioctl.h>
 #include <linux/fs.h>
 #include <asm/compat.h>
···
 	.name = "sclp",
 	.fops = &sclp_ctl_fops,
 };
-module_misc_device(sclp_ctl_device);
+builtin_misc_device(sclp_ctl_device);