ARM: S5PV210: Fix clk_get_rate issue with the clk_h100 clock

The clk_h100 clock represents the IMEM clock for the MSYS domain.
This clock rate of this clock is always half of the hclk_msys clock.
There is an issue when getting the clock rate of the clk_h100 clock
(clock get_rate hclk_h100 always returns clock rate that is equal to
the hclk_msys clock rate).

This patch modifies the following.

1. Moves the definition of the clk_h100 clock into the 'init_clocks'
   list with the appropriate parent, ctrlbit, enable and ops fields.

2. The name of the clock is changed from 'clk_h100' to 'hclk_imem'
   to represent more clearly that is represents the IMEM clock in
   the MSYS domain.

3. The function to get the clock rate of the hclk_imem clock is added.

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>