x86/pkeys: Simplify PKRU update in signal frame

commit d1e42077 upstream.

The signal delivery logic was modified to always set the PKRU bit in
xregs_state->header->xfeatures by this commit:

    ae6012d7 ("x86/pkeys: Ensure updated PKRU value is XRSTOR'd")

However, the change derives the bitmask value using XGETBV(1), rather
than simply updating the buffer that already holds the value. Thus, this
approach induces an unnecessary dependency on XGETBV1 for PKRU handling.

Eliminate the dependency by using the established helper function.
Subsequently, remove the now-unused 'mask' argument.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20250416021720.12305-9-chang.seok.bae@intel.com


Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>