kernel/hung_task: fix address space of proc_dohung_task_timeout_secs

kernel/hung_task: fix address space of proc_dohung_task_timeout_secs

The proc_dohung_task_timeout_secs() function is incorrectly marked
as having a __user buffer as argument 3. However this is not the
case and it is casing multiple sparse warnings. Fix the following
warnings by removing __user from the argument:

kernel/hung_task.c:237:52: warning: incorrect type in argument 3 (different address spaces)
kernel/hung_task.c:237:52:    expected void *
kernel/hung_task.c:237:52:    got void [noderef] __user *buffer
kernel/hung_task.c:287:35: warning: incorrect type in initializer (incompatible argument 3 (different address spaces))
kernel/hung_task.c:287:35:    expected int ( [usertype] *proc_handler )( ... )
kernel/hung_task.c:287:35:    got int ( * )( ... )
kernel/hung_task.c:295:35: warning: incorrect type in initializer (incompatible argument 3 (different address spaces))
kernel/hung_task.c:295:35:    expected int ( [usertype] *proc_handler )( ... )
kernel/hung_task.c:295:35:    got int ( * )( ... )

Link: https://lkml.kernel.org/r/20220714074744.189017-1-ben.dooks@sifive.com
Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
Cc: <Conor.Dooley@microchip.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>