m68knommu: include SDHC support only when hardware has it

The mere fact that the kernel has the MMC subsystem enabled (CONFIG_MMC
enabled) does not mean that the underlying hardware platform has the
SDHC hardware present. Within the ColdFire hardware defines that is
signified by MCFSDHC_BASE being defined with an address.

The platform data for the ColdFire parts is including the SDHC hardware
if CONFIG_MMC is enabled, instead of MCFSDHC_BASE. This means that if
you are compiling for a ColdFire target that does not support SDHC but
enable CONFIG_MMC you will fail to compile with errors like this:

    arch/m68k/coldfire/device.c:565:12: error: ‘MCFSDHC_BASE’ undeclared here (not in a function)
       .start = MCFSDHC_BASE,
            ^
    arch/m68k/coldfire/device.c:566:25: error: ‘MCFSDHC_SIZE’ undeclared here (not in a function)
       .end = MCFSDHC_BASE + MCFSDHC_SIZE - 1,
                         ^
    arch/m68k/coldfire/device.c:569:12: error: ‘MCF_IRQ_SDHC’ undeclared here (not in a function)
       .start = MCF_IRQ_SDHC,
            ^

Make the SDHC platform support depend on MCFSDHC_BASE, that is only
include it if the specific ColdFire SoC has that hardware module.

Fixes: 991f5c4dd2 ("m68k: mcf5441x: add support for esdhc mmc controller")
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Angelo Dureghello <angelo.dureghello@timesys.com>
Tested-by: Angelo Dureghello <angelo.dureghello@timesys.com>

arch/m68k/coldfire/device.c

@@ -554,7 +554,7 @@ static struct platform_device mcf_edma = {
 };
 #endif /* IS_ENABLED(CONFIG_MCF_EDMA) */
 
-#if IS_ENABLED(CONFIG_MMC)
+#ifdef MCFSDHC_BASE
 static struct mcf_esdhc_platform_data mcf_esdhc_data = {
 	.max_bus_width = 4,
 	.cd_type = ESDHC_CD_NONE,
@@ -579,7 +579,7 @@ static struct platform_device mcf_esdhc = {
 	.resource		= mcf_esdhc_resources,
 	.dev.platform_data	= &mcf_esdhc_data,
 };
-#endif /* IS_ENABLED(CONFIG_MMC) */
+#endif /* MCFSDHC_BASE */
 
 static struct platform_device *mcf_devices[] __initdata = {
 	&mcf_uart,
@@ -613,7 +613,7 @@ static struct platform_device *mcf_devices[] __initdata = {
 #if IS_ENABLED(CONFIG_MCF_EDMA)
 	&mcf_edma,
 #endif
-#if IS_ENABLED(CONFIG_MMC)
+#ifdef MCFSDHC_BASE
 	&mcf_esdhc,
 #endif
 };