powerpc: Revert switch to TEXT_TEXT in linker script

Commit edada399 broke the build on 64-bit powerpc because it moved the
__ftr_alt_* sections of a file away from the .text section, causing
link failures due to relative conditional branch targets being too far
away from the branch instructions.  This happens on pretty much all
64-bit powerpc configs.

This change reverts commit edada399 while preserving the update from
the *.refok sections to .ref.text that has happened since.

Signed-off-by: Tim Abbott <tabbott@mit.edu>
Requested-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>