SPEAr: clk: Add General Purpose Timer Synthesizer clock

All SPEAr SoC's contain GPT Synthesizers. Their Fout is derived from
following equations:

Fout= Fin/((2 ^ (N+1)) * (M+1))

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/spear/Makefile b/drivers/clk/spear/Makefile
index 1827036..9e64824 100644
--- a/drivers/clk/spear/Makefile
+++ b/drivers/clk/spear/Makefile
@@ -2,4 +2,4 @@
 # SPEAr Clock specific Makefile
 #
 
-obj-y	+= clk.o clk-aux-synth.o clk-frac-synth.o clk-vco-pll.o
+obj-y	+= clk.o clk-aux-synth.o clk-frac-synth.o clk-gpt-synth.o clk-vco-pll.o