[RFC] Introduce HAVE_IDE to support flexible IDE per arch configuration

[Sam Ravnborg]

Following patch introduce HAVE_IDE to support flexible per
arch or even per. sub-arch configuration of IDE support.
This patch is needed to allow arm to use the generic
drivers/Kconfig file.

Introducing HAVE_IDE so each arch explicit select HAVE_IDE
if supported allowed us to get rid of HAS_IOMEM which
is anyway overloaded.
And doing it this way is a much better way to document which
architectures that supports IDE.
Furthermore the decision if IDE is supported or not is
distributed.
Consider seeing this all over:

-if PCMCIA || ARCH_CLPS7500 || ARCH_IOP32X || ARCH_IOP33X || ARCH_IXP4XX \
-       || ARCH_L7200 || ARCH_LH7A40X || ARCH_PXA || ARCH_RPC \
-       || ARCH_S3C2410 || ARCH_SA1100 || ARCH_SHARK || FOOTBRIDGE \
-       || ARCH_IXP23XX
 source "drivers/ide/Kconfig"
-endif

Only s390 and um does not support IDE from my quick
investigation, if there are others let me know.
[Added linux-arch to catch all arch maintainers].

Comments?

	Sam