x86/fpu/signal: Fix missed conversion to correct boolean retval in save_xstate_epilog()

x86/fpu/signal: Fix missed conversion to correct boolean retval in save_xstate_epilog()

BugLink: https://bugs.launchpad.net/bugs/1967750
Fix the missing return code polarity in save_xstate_epilog().

 [ bp: Massage, use the right commit in the Fixes: tag ]

Fixes: 2af07f3a6e9f ("x86/fpu/signal: Change return type of copy_fpregs_to_sigframe() helpers to boolean")
Reported-by: Remi Duraffort <remi.duraffort@linaro.org>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1461
Link: https://lkml.kernel.org/r/20210922200901.1823741-1-anders.roxell@linaro.org
(cherry picked from commit 724fc0248d450224b19ef5b5ee41e392348f6704)
Acked-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>