arm: mach-k3: common: fix compile warnings with PHYS_64BIT on 32bit

Use uintptr_t instead of phys_addr_t where appropriate, so passing the
addresses to writel() doesn't result in compile warnings when PHYS_64BIT
is set for 32bit builds (which is actually a useful configuration, as
the K3 SoC family boots from an R5 SPL, which may pass bank information
based on gd->bd->bi_dram to fdt_fixup_memory_banks() etc., so PHYS_64BIT
is needed for fixing up the upper bank).

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>