powerpc: Include .BTF section

BugLink: https://bugs.launchpad.net/bugs/1873852

[ Upstream commit cb0cc635 ]

Selecting CONFIG_DEBUG_INFO_BTF results in the below warning from ld:
  ld: warning: orphan section `.BTF' from `.btf.vmlinux.bin.o' being placed in section `.BTF'

Include .BTF section in vmlinux explicitly to fix the same.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200220113132.857132-1-naveen.n.rao@linux.vnet.ibm.comSigned-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

arch/powerpc/kernel/vmlinux.lds.S

@@ -255,6 +255,12 @@ SECTIONS
 		*(.branch_lt)
 	}
 
+#ifdef CONFIG_DEBUG_INFO_BTF
+	.BTF : AT(ADDR(.BTF) - LOAD_OFFSET) {
+		*(.BTF)
+	}
+#endif
+
 	.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
 		*(.opd)
 	}