staging: et131x: Revert changes from previous commit

In commit 834d0ee3 (uintxy_t removal) not all changes were trival text replacements, some converted u64 -> dma_addr_t.
In some configurations dma_addr_t is a u32, meaning that some bit operations cause build warnings. From Randy Dunlap:

----------------
on i386 (X86_32) builds:

drivers/staging/et131x/et131x.c:2483:8: warning: right shift count >= width of type
drivers/staging/et131x/et131x.c:2531:8: warning: right shift count >= width of type
----------------

Removed these by reverting dma_addr_t back to u64 types, as well as
reverting some other non-trivial changes from the aforementioned commit.

Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Mark Einon <mark.einon@gmail.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>