clk: xgene: Delete duplicated name field

X-Gene clocks implement it's name in the clock private struct.
This is a duplication of the name field. We can delete the field
and rely on the common implementation to retrieve the name.

Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>