umd: Remove usermode driver framework

The code is unused since 98e20e5 ("bpfilter: remove bpfilter"),
therefore remove it.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/bpf/20250721-remove-usermode-driver-v1-2-0d0083334382@linutronix.de

Author: t-8ch

include/linux/usermode_driver.h

@@ -12,7 +12,6 @@ obj-y     = fork.o exec_domain.o panic.o \
 	    notifier.o ksysfs.o cred.o reboot.o \
 	    async.o range.o smpboot.o ucount.o regset.o ksyms_common.o
 
-obj-$(CONFIG_USERMODE_DRIVER) += usermode_driver.o
 obj-$(CONFIG_MULTIUSER) += groups.o
 obj-$(CONFIG_VHOST_TASK) += vhost_task.o
 

kernel/Makefile

@@ -1,8 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
-config USERMODE_DRIVER
-	bool
-	default n
-
 menuconfig BPF_PRELOAD
 	bool "Preload BPF file system with kernel specific program and map iterators"
 	depends on BPF