powerpc/64: Fix placement of .text to be immediately following .head.text

Do not introduce any additional alignment. Placement of text section
will be set by fixed section macros. Without this, output section
alignment defaults to 4096, which makes BookE text section start at
0x1000 when it is expected to start at 0x100.

This was introduced by commit 57f26649 ("powerpc: Use gas sections
for arranging exception vectors") and was caught with the scripted head
section checker (not yet merged).

Fixes: 57f26649 ("powerpc: Use gas sections for arranging exception vectors")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>