livepatch: doc: remove the limitation for schedule() patching

livepatch: doc: remove the limitation for schedule() patching

The Limitations section of the documentation describes the impossibility
to livepatch anything that is inlined to __schedule() function. This had
been true till 4.9 kernel came. Thanks to commit 0100301bfdf5
("sched/x86: Rewrite the switch_to() code") from Brian Gerst there is
__switch_to_asm function now (implemented in assembly) called properly
from context_switch(). RIP is thus saved on the stack and a task would
return to proper version of __schedule() et al. functions.

Of course __switch_to_asm() is not patchable for the reason described in
the section. But there is no __fentry__ call and I cannot imagine a
reason to do it anyway.

Therefore, remove the paragraphs from the section.

Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>