sh_eth: rename TRSCER bits

In all the SoC manuals the TRSCER register bits match the corresponding
EESR registers's bits, but only on the R-Car gen2 SoC those are named
RINT<n> and TINT<n>.  Follow the suit and rename the *enum* tag/entries
from DESC_I_* to TRSCER_*.

Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>