tqm85xx: create fixed_sdram() to do sdram setup

Also, change this code to use phys_size_t instead of long int.
Using common naming for this function will enable us to use the common
initdram() for 85xx going forward.  Other than the type change,
this is just a code rearrange.

Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>