eisa: consolidate EISA Kconfig entry in drivers/eisa

Let architectures opt into EISA support by selecting HAVE_EISA and
handle everything else in drivers/eisa.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul Burton <paul.burton@mips.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>