The base address for both the GPIO and the clock unit of the H6 memory map
have been typo-ed. Fix them to match the Linux DT and the manual.

The H6 code use neither of them, so this doesn't change or fix anything
in the real world, but should be corrected anyway.

The issue was found and reported by Github user "armlabs".

Change-Id: Ic6fdfb732ce1cfc54cbb927718035624a06a9e08
Signed-off-by: Andre Przywara <andre.przywara@arm.com>