clk: clk-fixed-factor: Use new macro CLK_OF_DECLARE_DRIVER

clk: clk-fixed-factor: Use new macro CLK_OF_DECLARE_DRIVER

Fixed factor clock has two initialization at of_clk_init()
time and also during platform driver probe. So declare the
fixed factor clock with CLK_OF_DECLARE_DRIVER instead of
CLK_OF_DECLARE.

See below commit for reference:
"clk: sunxi: apb0: Use new macro CLK_OF_DECLARE_DRIVER"
(sha1: 915128b621a05c63fa58ca9e4cbdf394bbe592f3)

Signed-off-by: Rajan Vaja <rajanv@xilinx.com>
Suggested-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>