powerpc/boot: Move the .got section to after the .dynamic section

Both .dynamic and .got are RELRO sections and should be placed
together, and LLD emits an error:

  ld.lld: error: section: .got is not contiguous with other relro sections

Place them together to avoid this.

Signed-off-by: Bill Wendling <morbo@google.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201017000151.150788-1-morbo@google.com