clk: sifive: Factor-out PLL library as separate module

To match SiFive clock driver with latest Linux, we factor-out PLL
library as separate module under drivers/clk/analogbits.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/clk/sifive/fu540-prci.c b/drivers/clk/sifive/fu540-prci.c
index 2d47ebc..56084db 100644
--- a/drivers/clk/sifive/fu540-prci.c
+++ b/drivers/clk/sifive/fu540-prci.c
@@ -37,10 +37,9 @@
 #include <errno.h>
 
 #include <linux/math64.h>
+#include <linux/clk/analogbits-wrpll-cln28hpc.h>
 #include <dt-bindings/clk/sifive-fu540-prci.h>
 
-#include "analogbits-wrpll-cln28hpc.h"
-
 /*
  * EXPECTED_CLK_PARENT_COUNT: how many parent clocks this driver expects:
  *     hfclk and rtcclk