of/platform: Fix microblaze build failure

Commit bf5db2f (microblaze: Use generic device.h) removes the
microblaze specific pdev_archdata and dma_mask.

At the same time, commit 591c1ee (of: configure the platform
device dma parameters) initializes the just removed field.
This causes all microblaze builds to fail.

Drop the unnecessary initialization.

Cc: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/of/platform.c

@@ -166,10 +166,6 @@ static void of_dma_configure(struct platform_device *pdev)
 	int ret;
 	struct device *dev = &pdev->dev;
 
-#if defined(CONFIG_MICROBLAZE)
-	pdev->archdata.dma_mask = 0xffffffffUL;
-#endif
-
 	/*
 	 * Set default dma-mask to 32 bit. Drivers are expected to setup
 	 * the correct supported dma_mask.