clk: fixed_rate: configure clock ID with CONFIG_CLK_AUTO_ID

clk: fixed_rate: configure clock ID with CONFIG_CLK_AUTO_ID

Update CLK ID to avoid 0 id, used for dummy clock with CCF
and to allow selection by clk_get_by_id, used to
get private data associated to the UCLASS_CLK device

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: Lukasz Majewski <lukma@denx.de>
Cc: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>