drivers: use devfdt_get_addr_index_ptr when cast to pointer

The fdt_addr_t and phys_addr_t size have been decoupled. A 32bit CPU
can expect 64-bit data from the device tree parser, so use
devfdt_get_addr_index_ptr instead of the devfdt_get_addr_index function
in the various files in the drivers directory that cast to a pointer.
As we are there also streamline the error response to -EINVAL on return.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>