spi: spi-aspeed-smc: use devfdt_get_addr_index_ptr

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 and devfdt_get_addr_size_index_ptr
function in the spi-aspeed-smc.c file. Also fix dev_dbg to be able
to handle both sizes. As we are there also streamline the error
response to -EINVAL on return.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Michael Trimarchi <michael@amarulasolutions.com>