x86/fpu/signal: Change return code of check_xstate_in_sigframe() to boolean

x86/fpu/signal: Change return code of check_xstate_in_sigframe() to boolean

BugLink: https://bugs.launchpad.net/bugs/1967750
__fpu_sig_restore() only needs success/fail information and no detailed
error code.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210908132526.024024598@linutronix.de
(backported from commit be0040144152ed834c369a7830487e5ee4f27080)
Acked-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>