UBUNTU: [Packaging] re-enable signing for ppc64el and s390x

Re-enable signing on these architectures, so that we can test secure
boot on them.

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

debian.master/rules.d/ppc64el.mk

@@ -8,7 +8,7 @@ kernel_file     = arch/powerpc/boot/vmlinux.strip
 install_file	= vmlinux
 no_dumpfile	= true
 do_extras_package = true
-opal_signed       = false
+opal_signed       = true
 do_tools_usbip    = true
 do_tools_cpupower = true
 do_tools_perf	  = true

debian.master/rules.d/s390x.mk

@@ -11,7 +11,7 @@ vdso		= vdso_install
 no_dumpfile	= true
 
 do_extras_package = true
-sipl_signed       = false
+sipl_signed       = true
 do_tools_usbip    = true
 do_tools_cpupower = true
 do_tools_perf     = true