net/altera_tse: use flush_dcache_range instead of flush_dcache

flush_dcache is not declared in the common.h API,
flush_dcache_range however is

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Ben Warren <biggerbadderben@gmail.com>
Cc: Thomas Chou <thomas@wytron.com.tw>
Acked-by: Thomas Chou <thomas@wytron.com.tw>