ARM: S5PV210: Add armclk of clksrc_clk clock type

This patch modifies the following.

1. Adds arm clock 'clk_armclk' of type clksrc_clk clock type.
2. Adds arm clock to the list of system clocks 'sysclks' for
   registering it along with other system clocks.
3. Modifies the armclk clock rate calculation procedure to be
   based on the new clk_armclk clock.

Signed-off-by: Thomas Abraham <thomas.ab@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>