blackfin: time-ts: Remove duplicate assignment

It seems that this assignment is done twice in a row. Remove the
duplicate assignment.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Steven Miao <realmz6@gmail.com>
Cc: trivial@kernel.org
Signed-off-by: Bob Liu <lliubbo@gmail.com>