clk/samsung: add support for pll2650xx

Add support for pll2650xx in samsung pll file. This PLL variant
is close to pll36xx but uses CON2 registers instead of CON1.

Aud_pll in Exynos5260 is pll2650xx and uses this code.

Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Signed-off-by: Tomasz Figa <t.figa@samsung.com>