powerpc/boot: Allow text relocations for pseries wrapper with binutils 2.46+

Binutils 2.46 changed the default linker behavior from '-z notext' to
'-z text', which treats dynamic relocations in read-only segments as
errors rather than warnings. This causes the pseries boot wrapper build
to fail with:

  /usr/bin/ld.bfd: arch/powerpc/boot/wrapper.a(crt0.o): warning:
    relocation against `_platform_stack_top' in read-only section `.text'
  /usr/bin/ld.bfd: error: read-only segment has dynamic relocations

The pseries wrapper uses '-pie' to create position-independent code.
However, crt0.S contains a pointer to '_platform_stack_top' in the .text
section, which requires a dynamic relocation at runtime. This creates
DT_TEXTREL (text relocations), which were allowed by default in binutils
2.45 and earlier (via implicit '-z notext') but are now rejected by
binutils 2.46+.

Add '-z notext' linker flag to explicitly allow text relocations for
the pseries platform, similar to what is already done for the epapr
platform. This restores the previous behavior and allows the boot
wrapper to build successfully with binutils 2.46+.

Signed-off-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Tested-by: Anushree Mathur <anushree.mathur@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260525161601.32097-1-amachhiw@linux.ibm.com

arch/powerpc/boot/wrapper

@@ -262,6 +262,7 @@ pseries)
     if [ "$format" != "elf32ppc" ]; then
 	link_address=
 	pie=-pie
+	notext='-z notext'
     fi
     make_space=n
     ;;