ARM: 6703/1: SPEAr: update clk API support

- Add support for divisor per parent clock
- Add ENABLED_ON_INIT feature in clk
- Add clk_set_rate(), round_rate_index & clk_round_rate()
- Simplify clk_recalc functions
- Add/update clock definitions

Reviewed-by: Stanley Miao <stanley.miao@windriver.com>
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: shiraz hashim <shiraz.hashim@st.com>
Signed-off-by: Rajeev Kumar <rajeev-dlh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>