m68k: coldfire: drop ISA_DMA_API support

After a build regression report, I took a look at possible users of
CONFIG_ISA_DMA_API on m68k and found none, which Greg confirmed. The
CONFIG_GENERIC_ISA_DMA option in turn is only needed to implement
ISA_DMA_API, and is clearly not used on the platforms with ISA support.

The CONFIG_ISA support for AMIGA_PCMCIA is probably also unneeded,
but this is less clear. Unlike other PCMCIA implementations, this one
does not use the drivers/pcmcia subsystem at all and just supports
the "apne" network driver. When it was first added, one could use
ISA drivers on it as well, but this probably broke at some point.

With no reason to keep this, let's just drop the corresponding files
and prevent the remaining ISA drivers that use this from getting built.

The remaining definitions in asm/dma.h are used for PCI support.

Link: https://lore.kernel.org/lkml/9e5ee1c3-ca80-f343-a1f5-66f3dd1c0727@linux-m68k.org/
Cc: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/m68k/Kconfig.bus

@@ -56,16 +56,6 @@ config ATARI_ROM_ISA
 	  The only driver currently using this adapter is the EtherNEC
 	  driver for RTL8019AS based NE2000 compatible network cards.
 
-config GENERIC_ISA_DMA
-	def_bool ISA
-
 source "drivers/zorro/Kconfig"
 
 endif
-
-if COLDFIRE
-
-config ISA_DMA_API
-	def_bool !M5272
-
-endif