pata_cs5536: Add support for non-X86_32 platforms

pata_cs5536 does work on the other platforms(e.g. Loongson, a MIPS
variant), so, remove the dependency of X86_32 and fix the building
errors under the other platforms via only reserving the X86_32 specific
parts for X86_32.

pata_amd also supports cs5536 IDE controller, but this one saves about
33k for the compressed kernel image(vmlinuz for MIPS).

Signed-off-by: Zhang Le <r0bertz@gentoo.org>
Signed-off-by: Chen Jie <chenj@lemote.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>