powerpc/32: Include .branch_lt in data section

When building a 32 bit powerpc kernel with Binutils 2.31.1 this warning
is emitted:

 powerpc-linux-gnu-ld: warning: orphan section `.branch_lt' from
 `arch/powerpc/kernel/head_44x.o' being placed in section `.branch_lt'

As of binutils commit 2d7ad24e8726 ("Support PLT16 relocs against local
symbols")[1], 32 bit targets can produce .branch_lt sections in their
output.

Include these symbols in the .data section as the ppc64 kernel does.

[1] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;h=2d7ad24e8726ba4c45c9e67be08223a146a837ceSigned-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Alan Modra <amodra@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/vmlinux.lds.S

@@ -319,6 +319,7 @@ SECTIONS
 		*(.sdata2)
 		*(.got.plt) *(.got)
 		*(.plt)
+		*(.branch_lt)
 	}
 #else
 	.data : AT(ADDR(.data) - LOAD_OFFSET) {