[IA64] Clean up linker script using standard macros.

Aside from using fewer output sections and moving some data around,
the main side effect of this change is changing the alignment of some
sections. In particular:

* cachline-aligned and read_mostly data are now aligned to
  SMP_CACHE_BYTES. (Previously, they were laid out consecutively after
  a PAGE_SIZE alignment)
* .init.ramfs is now page-aligned, per the INIT_RAM_FS
  macro. (Previously it had no explicit alignment).

Signed-off-by: Nelson Elhage <nelhage@ksplice.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>