kexec-tools: Fix build with LLD linker

kexec-tools: Fix build with LLD linker

With hardcoded -Ttext,0x10000 and newer toolchains emitting
.note.gnu.property before .text, the link can fail with an overlap.

Provide a minimal linker script that:
  - sets the image base to 0x10000,
  - places .text first at exactly 0x10000,
  - moves .note.gnu.property after .text,
  - optionally fixes .bss at 0x12000.

Works with both ld.bfd and LLD 21+.

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>