powerpc/mm: Simplify loop control in parse_numa_properties()

The flow of the main loop in parse_numa_properties() is overly
complicated. Simplify it to be less confusing and easier to read.
No functional change.

The end of the main loop in parse_numa_properties() looks like this:

	for_each_node_by_type(...) {
		...
		if (!condition) {
			if (--ranges)
				goto new_range;
			else
				continue;
		}

		statement();

		if (--ranges)
			goto new_range;
		/* else
		 *	continue; <- implicit, this is the end of the loop
		 */
	}

The only effect of !condition is to skip execution of statement(). This
can be rewritten in a simpler way:

	for_each_node_by_type(...) {
		...
		if (condition)
			statement();

		if (--ranges)
			goto new_range;
	}

Signed-off-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>