ARM: 6926/1: SPEAr clock: Define common clk_init routine in plat/clock.c

Define common clk_init routine in plat/clock.c for calling recalc_root_clocks.
This routine will be used for any common code across all machine families.
Whereas family specific spear*xx_clk_init routines will be used for family
specific code.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>