powerpc/fsl: Enable runtime patching if nospectre_v2 boot arg is used

BugLink: https://bugs.launchpad.net/bugs/1830176

commit 3bc8ea86 upstream.

If the user choses not to use the mitigations, replace
the code sequence with nops.
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/powerpc/kernel/setup_32.c

@@ -320,6 +320,7 @@ void __init setup_arch(char **cmdline_p)
 	if ( ppc_md.progress ) ppc_md.progress("arch: exit", 0x3eab);
 
 	setup_barrier_nospec();
+	setup_spectre_v2();
 
 	paging_init();
 

arch/powerpc/kernel/setup_64.c

@@ -735,6 +735,7 @@ void __init setup_arch(char **cmdline_p)
 		ppc_md.setup_arch();
 
 	setup_barrier_nospec();
+	setup_spectre_v2();
 
 	paging_init();