powerpc/ftrace: Fix confusing help text for DISABLE_MPROFILE_KERNEL

powerpc/ftrace: Fix confusing help text for DISABLE_MPROFILE_KERNEL

BugLink: http://bugs.launchpad.net/bugs/1691369
commit 496e9cb5b2aa2ba303d2bbd08518f9be2219ab4b upstream.

The final paragraph of the help text is reversed. We want to enable
this option by default, and disable it if the toolchain has a working
-mprofile-kernel.

Fixes: 8c50b72a3b4f ("powerpc/ftrace: Add Kconfig & Make glue for mprofile-kernel")
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>