[ARM] fix section-based ioremap

Tomi Valkeinen reports:
  Running with latest linux-omap kernel on OMAP3 SDP board, I have
  problem with iounmap(). It looks like iounmap() does not properly
  free large areas. Below is a test which fails for me in 6-7 loops.

	for (i = 0; i < 200; ++i) {
		vaddr = ioremap(paddr, size);
		if (!vaddr) {
			printk("couldn't ioremap\n");
			break;
		}
		iounmap(vaddr);
	}

The changes to vmalloc.c weren't reflected in the ARM ioremap
implementation.  Turns out the fix is rather simple.

Tested-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>
Tested-by: Matt Gerassimoff <mgeras@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>