powerpc: Fix inverted SET_FULL_REGS bitop

powerpc: Fix inverted SET_FULL_REGS bitop

BugLink: https://bugs.launchpad.net/bugs/1919492
commit 73ac79881804eed2e9d76ecdd1018037f8510cb1 upstream.

This bit operation was inverted and set the low bit rather than
cleared it, breaking the ability to ptrace non-volatile GPRs after
exec. Fix.

Only affects 64e and 32-bit.

Fixes: feb9df3462e6 ("powerpc/64s: Always has full regs, so remove remnant checks")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210308085530.3191843-1-npiggin@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>