[1/16][binutils][AARCH64]Add relocation support for large memory model. [BFD] simply refactor to facilitate further patch.

[Nick Clifton]

Hi Renlin,

> bfd/ChangeLog:
> 2015-09-08  Renlin Li  <renlin.li@arm.com>
>
>      * elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Change if to
>          switch statement.

Approved, please apply.

Cheers
   Nick