SPEAr: clk: Add VCO-PLL Synthesizer clock

All SPEAr SoC's contain PLLs. Their Fout is derived based on following equations

- In normal mode
  vco = (2 * M[15:8] * Fin)/N

- In Dithered mode
  vco = (2 * M[15:0] * Fin)/(256 * N)

pll_rate = vco/2^p

vco and pll are very closely bound to each other,
"vco needs to program: mode, m & n" and "pll needs to program p",
both share common enable/disable logic and registers.

This patch adds in support for this type of clock.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Reviewed-by: Mike Turquette <mturquette@linaro.org>
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 24aa714..0f5e03d 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -2,3 +2,6 @@
 obj-$(CONFIG_CLKDEV_LOOKUP)	+= clkdev.o
 obj-$(CONFIG_COMMON_CLK)	+= clk.o clk-fixed-rate.o clk-gate.o \
 				   clk-mux.o clk-divider.o clk-fixed-factor.o
+
+# SoCs specific
+obj-$(CONFIG_PLAT_SPEAR)	+= spear/